Other mistake: When Frank and the Ghost of Christmas Past are at the office Party where the younger Frank is still working, as they stand by the entrance door two women leaving move in closer to try and avoid bumping them - despite the fact that the Ghost said earlier they couldn't be seen or affect what's going on.
Scrooged (1988)
1 other mistake - chronological order
Directed by: Richard Donner
Starring: Bill Murray, John Glover, Karen Allen, John Forsythe
Continuity mistake: Near the end of the film before Frank starts singing, watch the guy to his left (screen right) in the plaid shirt. He goes from being next to him to behind him and jumps around a few times in the scene.
Earl Cross: Here Francis, I've got something for you. Merry Christmas.
Frankie Cross: A choo-choo train?
Earl Cross: No, it's five pounds of veal.
Frankie Cross: But Daddy I asked Santa for a choo-choo.
Earl Cross: Then go out and get a job and buy a choo-choo.
Trivia: Bill Murray slipping out of the restaurant wasn't scripted, he just slipped on wet steps.
Question: When Frank travels into the future and sees an older Calvin sitting on the floor, Calvin glances up. Did Calvin see Frank?
Answer: It's a vision, not reality, so one could interpret it either way. I think it's more powerful if Calvin is seeing Frank, silently accusing him of being (at least partially) responsible for his (Calvin's) situation.