Character mistake: In the very first scene in the film, the magazine covers are flashing up. There is an article called 'How to get a better bod in 5 days.' If you read the beginning of the article it says 'It Can Done.'
Character mistake: When Billy comes back from high school to visit his 3rd grade class, Ms. Vaughn is teaching prime numbers. The board reads "1, 3, 5, 7, 11" with the words "prime numbers" below it. "1" is not a prime number and it is written on the board, and "2" is a prime number and it is not written on the board.
Character mistake: When the Tradewind arrives at the island, captain Hilliot says, "They might not be civilized," to which Richard replies, "Civilized: c-i-v-i-l-i-Z-I-D."
Character mistake: In Frank Sinatra's scene in the taxi cab, when the girl is singing "Come Up to My Place," he rolls the cab window down and when he rolls it back up, he catches the front of his hair (the quiff) and has to roll the window back down to release it.
Character mistake: Gail reads right through Katie's poor excuse about crotcheting, and says she won't go to the ball "after what you pulled today with Guy." She did not do it (well she didn't do anything, but 'supposedly did') today, but yesterday. (00:31:00)
Character mistake: When Mollie goes to Albert's office for the first time since having Mickey, Albert asks if he is walking yet, and she says no. In the next scene with Mickey, he walks, and is walking when he visits Albert's office.
Character mistake: After George reads his speech to Lucy, she says it was fine except for "the split infinitive near the end." There was no split infinitive. (For example, "to boldly go" is a split infinitive; "to go boldly" is not.) (01:29:00)
Suggested correction: She was joking. She was trying to find something to criticise in his speech because she was still angry so she made something up.
Character mistake: Throughout the film, Lucy's aunt is called "Patsy." In the final scene Lucy refers to her as "Patty."
Character mistake: Jean rolls, kneads, and flattens the dough a few times, repeating the steps to give the image of still preparing the dough. After the dough was flattened, it was well-shaped (round, higher, and more compact) then flat again. The way she was shaping the dough suggests she was making biscuits, but biscuit dough should not be handled that much (or the biscuits would be flat and not flaky). (00:18:00 - 00:19:00)
Character mistake: When Holly and Amber go to see Amber's uncle at the Bistro, they say the 'report' is due tomorrow. However that day will be Sunday (no school!), as previously it was mentioned that the day was Saturday.
Character mistake: When Adams is chewing out Altaira for flirting with his crew, he says that he is "in command of 18 perfect physical specimens." With him, that would make for a total crew of 19 on the C57-D. But the complete cast only shows 18 names, including Walter Pidgeon as Morbius and Anne Francis as Alta. (And discounting Robby and his human handlers). Thus it would seem Adams is off by three. He has only 15 under his command. I've tried counting them when they're in group shots, but can't see everyone.
Character mistake: In every scene George is with Mary, she never once wears glasses. However, when he meets her coming from the library after he was never born, she is wearing glasses. George is shown how he has influenced all the people in Bedford Falls over his lifetime, but having Mary's eyesight degrade to the point of needing glasses isn't one of them.
Character mistake: Mac's cousin says that even if Nick wasn't a cop, he'd have to hate Mac's guts. He says that Mac wears a Rolex and Nick wears a Timex - not true. Nick is wearing a Rolex, also.
Character mistake: Sam and Maurey were watching TV news coverage of Kennedy's assassination (11/22/63). When Petey got home (around 12:05 PM MST), he tried to change the channel, then said, "Mom, Maurey won't let me watch 'Rocky'." Laurabel/Mom said, "You know he watches 'Rocky' every afternoon." But school was let out early due to the assassination, so Petey would normally be in school at noon and therefore not be able to watch "Rocky" at that time in the afternoon. (00:21:30 - 00:23:17)
Character mistake: During the military parade, check the lady behind the soldier on the left. She can't help stare at the camera the whole time before the soldiers arrive. (00:07:03)
Character mistake: When Gilmore radios for backup during the Monument Valley chase, he is told additional officers will join them in Blanding. Kowalski hears this on his scanner as they pass a sign saying Blanding is 14 miles away. Kowalski then stops dead in the road and turns around, and the troopers do the same, yet when Sgt. Preston grabs the shotgun, he justifies firing on Kowalski saying "We're coming on to Blanding!" In actual fact they would be heading away from Blanding.
Character mistake: Claudia says she is 40, her daughter is 16, it is referenced that it was a young pregnancy, however she would have been 24 when she had Kit, hardly abnormally young.
Suggested correction: 24 is still young and she doesn't say anything about being "abnormally young." Plus, in 1979, the mean age for first time mothers was around 25.5 (rising to around 28.6 in 1995), so she was on the young side of first time mothers. If she had said she was a teenager when she got pregnant, that would be a mistake.
Character mistake: When Andy calls Linda, as Linda and Steve are hooking up, he addresses her (on the answering machine) as Tammy.
Character mistake: Ashley should be smart enough to know not to wear high heels while buffing the bowling alley lane. They might break or scuff up the floor, she should've worn sneakers or sandals.
Character mistake: According to her biography found in the library, Elise was born November 11, 1885, but William Robinson tells Richard that he met Elise when she was 16 years old, in March, 1903, at which time she would have been 17.