Character mistake: When Lauren is playing roulette, she has $14,000 worth of chips sitting on red - if she wins, she gets double, $28,000; and if she loses, she loses all of the $14,000 - but the croupier is troubled and says to Lauren that she hasn't got enough to cover the bet, which is ridiculous; all her $14,000 chips are sitting on red, what more does she need? Even the head croupier is called in, and, after much chatting, all the other players are asked to take their chips away as only Lauren is playing this round, which is ridiculous: All they have to lose is $28,000; that's nothing for them.
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.
Suggested correction: It's possible that working in the library in low light for years may have accelerated a decline in her eyesight that might not otherwise have occurred in the original timeline.
Character mistake: The score board during the game shows the Gas House Gorillas have the scores 10, 28, 16 and 42, for a total of 96 runs. But later on the announcer gives the score as "Bugs Bunny 96, Gas House Gorillas 95."
Character mistake: In the "Casey At The Bat" sequence, the narrator says "The score is 4 to 2 with but an inning left to play." However, the scoreboard shows that eight and a half innings have been played, and only a half-inning remains.