In the cab, on the way to the hospital, Mollie shouts that her water just broke and James looks back apparently seeing a mess, but when she gets to the hospital, her overalls are perfectly dry with no evidence of her water breaking.
James introduces himself to Mikey and he shakes his hand with his right hand. In the next shot James is shaking Mikey's hand with his left hand.
When Molly is dressing Mikey for his first meeting with Albert, she asks him what outfit he wants to wear. In the shot with him saying neither, he is already in the white lamb overalls.
James carries a sleeping Molly to bed. When he first picks her up, her hands fall on her chest. However, in the next shot, her arms are wrapped around his neck.
James attempts to light a cigarette in Molly's apartment to her disgust. However there is a sign displayed in his cab that states the driver is allergic to cigarette smoke.
During the musical montage, Molly is on a weight scale and adjusts it to 136 pounds. As far along as she was at that time (she had already heard the baby's heartbeat), she would weigh more than 136 pounds.
When Molly and Harry are at the restaurant and Harry signals the waiter to place the bill next to Molly, the bill shows the subtotal of $75.00 and tax of $0.86 for a total of $76.85, which is incorrect. In actuality, the total amount for their mean was $76.93.
When Molly and Harry are at the restaurant and Harry signals the waiter to place the bill next to Molly, the bill shows the subtotal of $75.00 and tax of $0.86 for a total of $76.85, which is incorrect. In actuality, the total amount for their meal was $76.93.
When the channels are being switch by a remote control from a football game to a snuggle's commercial, the channel number stays at 03.
When Molly and James are in the airplane and he's telling her to "take his stick", you can see the wall of the hangar behind them during the front shot.
Mikey's birthday is July 3rd, but Molly is wearing a long sleeve sweater and overalls the day she gives birth, both of which would be too hot in summer.
At one point, Molly is in the streets with Mikey and we see a Starbucks Coffee in the background. Starbucks did not make it to the east coast until the early-1990s.
When James asks Mollie about Albert, he says "Where the hell has he been all year?", but it's clear by his lips that he actually said the f-word, and "hell" was dubbed over it.
In the far shots during the chase scene at the end it is obvious that the driver and passenger in the taxi are Travolta and Alley's stunt doubles.
When James is driving Molly to the hospital, they pass a window and you can very obviously see the camera sitting on the hood of the taxi.
When James is driving Molly and Mikey to pick up his grandpa, they pass several windows that reflect the camera and crew on the other side of the taxi.
During the very last scene James and Mikey go to a hospital to see Molly. While walking into her hospital room you can see it's obviously a set/sound stage when you look up at the top, in the corner(s), you will see it for a few good seconds.
Even though this is supposed to be taking place in New York City, the outdoor filming locations are clearly not in New York City.
When James goes to Mollie's apartment to return her purse after Mikey is born, James says to Mikey, "How you doing, Mikey? I'm James." How did he know his name was Mikey if Mollie never told him?
Mollie's blind date stresses the importance of a Notre Dame football game on TV by saying "it's the playoffs." In 1989, Notre Dame participated in Division I (now the FBS), which had not yet incorporated a playoff system.
When James asks Albert who Mikey's favorite rock star is, the answer is Michael Jackson, although James pronounces it "Jackshun".