The length of Wong's hair changes in various scenes.
(at around 15 mins) When Strange and Chavez are eating pizza together, the slice Chavez is holding folds and unfolds between cuts.
(at around 1h 23 mins) Doctor Strange unlocks the door to the Gap Junction by placing 838 Strange's broken wristwatch in a gap in the center of the handle. When the door opens however, the watch and the space it was placed in are missing.
Just after 13 minutes in, once Dr Strange has speared the 1 eyed octopus monster it falls to its death and is viewed it from above. All 8 tentacles are intact even though two were cut off in the fight previously.
(at around 56 mins) Strange does not try to manually remove his wrist cuffs. They might be "visibly very loose", but they're also magic.
A normal person cannot "wake up" from a severe head injury in a jolt as portrayed by Wong. The Sorcerer Supreme may have superhuman abilities in this matter.
On Earth-838, red means go and green means stop. This means that tail lights and brake lights on all vehicles should have green lens covers. But they're just red, like normal.
(at around 1h 16 mins) When Strange is falling after being thrown onto the wall, the stunt double makes sure to hide his face with his hand, and rapidly turns his head towards the wall.
(at around 3 mins) America is grabbed by the creature by her right arm (not strongly enough to pull her sideways though) and she merely looks at her arm instead of trying to pull it away and fighting it, revealing it to be CGI.
(at around 56 mins) The "fish tanks" have obvious vertical openings between the panels. They are more fragile and could be bent, or the panels broken.
(at around 10 mins) When America runs away towards the camera from the one-eye calamari creature, the CGI green screen is obvious.
Whether heard from outside or inside the "fish tanks", all the dialogue, sounds, and voices are the same volume.
(at around 41 mins) The pizza ball vendor accuses the main (universe 616) Dr. Strange of stealing universe 838 Strange's cape. Later, in a flashback (at around 1h 9 mins), 838 Strange's cape is blue, and 616 Strange's cape is red.
However, Pizza Poppa accuses Strange of stealing the cape from the Strange Museum, which implies that it is from an older costume. Strange-838 may have worn a red cape in the past before switching to a blue cape later.