Continuity mistake: The time gap between past and present seems to vary in different series, from 53 to 55 years.
Goodnight Sweetheart (1993)
1 continuity mistake in show generally - chronological order
Continuity mistake: When Phoebe kisses Gary, there's no lipstick mark on his cheek. But when he gets home, one has somehow appeared.
Ron Wheatcroft: How do you know the future you've got now is the same future you're going to have if something in the past is different from the last time you went back to the future?