Character mistake: When Lucky the dog is chasing Slick the cat, into John and Ariel Gustafson's house, Ariel yells out her husband's name, she actually yells out the actor's real name Jack instead of John, the character's name. Pay close attention, it could be easily missed. (01:07:10)
Character mistake: Lucy asks the hot dog man for the usual: mustard and Coke. She gets the hot dog but no Coke.
Character mistake: When young Alan is talking young Sarah, he says that he found a board game at the factory. Alan didn't find the game at the factory. He found the game across from the factory at a construction site.
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: Circus Liquor is actually located in North Hollywood, not Sun Valley (although Sun Valley is just a few short miles away from there).
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: At one point Michael J. Fox says he doesn't want to end up in Danbury Correctional, why not? The Federal prison in Danbury CT would be a dream come true since he would be the only male inmate, as it became all-female in 1993.
Suggested correction: The construction might very well be part of the factory, a new factory building for example.
lionhead
The sign at the construction site said it was an "Executive Office Annex" that they were building.
Bishop73
Even though the sign said it was an Annex, construction was still being done outside of the main factory where Alan found the game. Not inside of the main factory itself.