In the "present," Data must leave his station and go to main engineering in order to modify the deflector dish to emit an inverse tachyon pulse. When Picard suggests he perform that same modification in the "past," he does so entirely from his console on the bridge (the helm console at that).
Governor Worf gives the Pasteur permission to enter Klingon space, "But only if I come with you. I am familiar with the Neutral Zone." It was stated earlier that the Neutral Zone had been abolished.
When Picard appears before Q's "court," Q explains that the trial "never ended." Yet in Season 2's Q Who (1989), when Riker says Q "put us on trial for the crimes of humanity", Q replies that they were exonerated.
When Picard interrupts Worf and Troi's date at the beginning of the episode, they are standing parallel to the doorway to her quarters, about to kiss. When time is restored and Picard performs the same action, Worf and Troi are now positioned at right angles to the doorway.
In the parts taking place together with Encounter at Farpoint (1987), Data mistakenly wears the insignia of Lieutenant Junior Grade even though he's a Lieutenant Commander, as shown in the original pilot.
When the future Enterprise is at warp and the senior staff is in Ten Forward, stars are seen through the view ports streaking from the port side of the ship to the starboard. Since Ten Forward is, as the name implies, located in the forward-most part of the ship, the stars should be coming towards them, not moving from one side of the ship the the other.
O'Brien in the past wears the rank insignia of Ensign but is called "Chief". A Chief is an NCO, not an officer.
The temporal anomaly was read as being an intersection of tachyon beams from the 3 different time line Enterprises. In the future time line, it was the USS Pasteur that initiated the tachyon beam, not the Enterprise. This is often considered a plot hole, but technically, Data is the one who found the discovery in the present time. His exact words were "The two other pulses have the exact same amplitude modulation as our own pulse. It is as if all three originated from the Enterprise." It is logical to presume Data, having been the one in all three time periods to help make the pulse, made the beams the same and in this present time made the assumption all three were from the Enterprise.
Deanna remembers having a reception in Ten Forward for Captain Picard's arrival seven years ago. Although Ten Forward was not introduced until the second season, it stands to reason that, being a major part of the ship, it must have existed from the beginning.
Although the events of the past time-line are not congruent with those from Encounter at Farpoint (1987), one can assume that at least the outset (i.e. Picard's shuttle transport to the Enterprise] did actually happen. His remark to Tasha Yar that she "looked very familiar" suggests that they met officially for the first time on that occasion. This, however, is in clear contradiction to the story Picard told in Legacy (1990) about his first encounter with Yar. However, Jean-Luc Picard has gone back in time at this point. His memory of Tasha Yar extends from his first trip on the Enterprise. He recognizes her, but he doesn't know from where, because his mind doesn't remember the future that already happened. After he comes back from the past, he tells Counselor Troi, "Tasha. I was just with Tasha in the shuttle." His present memory of her was affecting his past memory of possibly knowing her.
On the bridge 7 years in the past, Data is seated at the helm position while Chief O'Brien is at ops. As Data is the ship's operations officer, he should be at the ops console. However, their positions are accurate to Encounter at Farpoint (1987), and apparently the functions of their consoles swap afterwards.
When Tasha Yar is first approaching the Enterprise she approaches from the front under the saucer section. It would be much more simple and safer to fly over the saucer section then simply turn around into the shuttle bay. For safety's sake the approaches to the ship would be strictly controlled from a central station on the ship or the repair pod. Each shuttle leaving or arriving would be given clearance and vectors to fly which would avoid collisions. They would be the safest routes to and from the ship. The route Yar is flying would never be authorized. However, Tasha was giving The Captain a tour of the exterior of the ship, like Scotty did in Star Trek: The Motion Picture (1979).
Each season of the series, Worf's head ridges change slightly but noticeably. In the past scenes in this episode, Worf has his season seven ridges instead of his season one ridges.
In the early seasons of the show, Troi spoke with a fictional "Betazed" accent (reportedly so that, between herself and Picard, the show would not have an overwhelmingly "British" presence on the bridge). Gradually, Marina Sirtis was allowed to transition into using her natural English accent for the character so that, by later seasons, she was just speaking in her normal voice. Here, in the scenes set at the start of season 1, she is using her natural English accent, rather than the Betazed accent that would have been appropriate to the time period.
In the past timeline, after Counselor Troi talks with Captain Picard in his ready room about crew discomfort and her romance with Commander Riker, she exits to the bridge at the end of the scene. Just as the ready room door slides shut, the door to the battle bridge can be seen in the background. The striping on the battle bridge door matches the styling of the Enterprise-D bridge of the future timeline, not the past.
The elder Picard's false mustache can be seen pulling away from his face in several shots.
The Enterprise bridge was, as much as was feasible, restored to its season 1 configuration for the scenes set in the past. However, in at least one shot of Data and O'Brien at their stations, they are seen in the more upright chairs introduced in later seasons, rather than in the reclined chairs from season 1. The reclined chairs appear in the majority of shots on the "7 years earlier" bridge.
In the future timeline, Geordi explains that he came to see Picard because he'd heard about his illness, remarking that "Leah [Geordi's wife] still has a few friends at Starfleet Medical. Word gets around." It would be highly inappropriate and a breach of doctor/patient privilege for a medical professional to discuss a patient's condition with anyone other than the patient without said patient's consent.
When the Pasteur is under attack by two Klingon warships, Beverly asks Geordi to get the warp engines back online. Geordi is not a member of her crew, nor even an active duty Starfleet officer. The ship would have had its own dedicated engineering staff whom Beverly would have given orders to, not a civilian visitor with an engineering background.
At one point, in the "past," Picard leaves the bridge and puts Tasha Yar in command. Data is the second officer of the ship and, since Riker is not onboard, the next senior-most officer in the chain of command. Yar is the chief of security and, if her position in the chain of command is comparable to Worf's (her successor as security chief) in later seasons, the ship's third officer. Data should have been left in charge, not Yar.
When asked how long until they reach the center of the anomaly, Data replies, "At least 30 seconds, sir." Both the Enterprise's computer and Data are capable of far greater precision than "at least 30 seconds."
The captain's chair on the Enterprise from the "past" time. The bridge of the Enterprise that is on its way to Farpoint station has the captain's chair with fixed arm rests. The chair from season 1 had flip up computer pads. Also the chairs next to the first officer's chair and counselor's chair were different in the first season set.
When we see the crew from the past enter the Conference Room, you can see horizontal lights below the windows, even though these had only been introduced to the set in season 5.
Anytime they showed the bridge on the first season Enterprise D, the moving lights underneath the main view screen move from the center to the outer edges, where actually during season 1, the lights moved from the outer edges to the center.
During the first season, the back bridge stations are bookended by blank beige walls. At the start of season 2, LCARS screens were added to cover those walls. The past Enterprise retains those season 2 LCARS screens.
In the observation lounge scenes set during the Farpoint mission, two LCARS screens can be seen on either end of the room. Display screens were first installed in that room during the second season. In the first season, paintings were displayed in the lounge.
The "beardless" Riker's dialogue doesn't match the visuals (stock footage is taken from The Arsenal of Freedom (1988)).
During the initial scene, Worf mentions they were in the holodeck on the Black Sea coast, then Deanna says they experienced the ocean breeze. Well, the Black Sea is not an ocean.
The anomaly is said to grow backwards in time. Yet, in the future when created by the tachyon beam it seems to grow normally in time as it is larger sometime after the creation.
The anti-time anomaly is increasing going back in time, thus it is decreasing as we go forward in time. Therefore it must exist when the "old" Picard goes to look for it and it will cease to exist in the future. The statement that it was created in the past six hours would not be possible.
In the past, Picard first encounters Data as the latter wanders through the engine room and comments on Chief O'Brien's figure of speech. Picard then welcomes Data aboard, implying that Data boarded the ship after the ceremony in the shuttle bay. As the operations officer of the ship and a member of the command crew, Data should have gone straight to see Picard upon boarding, not wandered around engineering.
In the future timeline, it makes absolutely no sense for a medical ship such as the Pasteur to be equipped and sent out close to enemy territory with minimal defenses as shown. Yet Starfleet equips the Enterprise with a phaser cannon that can blast through the shields of the Klingon ships.
In the future timeline, after the Enterprise destroys the first Klingon ship, the crew does not bother to destroy the second one.
Just before the Farpoint-era Enterprise explodes, Lt. Yar announces that the warp core containment is failing and that she can't stop it. As tactical officer, it would not be her duty to repair the warp core, nor would her station be set up to affect any changes on the warp core. That would be the responsibility of the engineering department and such work would be carried out in the actual engine room.
Beverly thinks that because of the accumulation of acetylcholine in Picard's brain, he now has about two days worth of new memories. Acetylcholine is a neurotransmitter, which - aside from its functions in the activation of muscles - is rather associated with the short-term memory, which lasts no longer than several seconds to a minute.
When the helmsman of the Pasteur addresses Beverly as "Captain Picard," Jean-Luc is surprised to find that she kept the name after their divorce. He was said to have contacted her about gaining passage to the Devron system aboard her vessel. It would not be possible to contact her through any channel without having a current name. He should have known well before boarding that she'd kept the name.
When deciding to proceed to Farpoint, Picard orders Worf back to his station. In season 1, Worf was a bridge relief officer whose duty was to take over the function of any other officer who was called away (say, for example, if Tasha or Data were sent on an away mission, Worf would take over at tactical or ops). He had no dedicated station.
When leaving Ten Forward, Admiral Riker tells Governor Worf that they "could use a hand." While this is meant to be an olive branch from Riker to Worf (after their decades-long estrangement), it is unclear with what they could use his help with. Worf is no longer a commissioned Starfleet officer, nor does he have any expertise in temporal mechanics. Indeed, once on the bridge, all Worf does is stand behind the Enterprise's tactical officer.