Continuity mistake: In the first episode, when they meet as children, they seem to be about the same age. But later episodes refer to Greg as a 32-year-old lawyer, and after 2-3 years of marriage, Dharma is having her rebirthday party, which happens every 7 years. She is 28 then, so it seems like Greg is at least 5 years older, which is very noticeable as children.
Dharma & Greg (1997)
1 continuity mistake in season 2
Starring: Jenna Elfman, Thomas Gibson, Joel Murray, Mimi Kennedy
The Ex-Files - S1-E5
Continuity mistake: When Dharma is visiting her uncle (a dentist) and she's in the dentist chair, she has a little spot of water on her bib, the shot moves, then it moves again and the spot isn't there anymore.
Greg: You wanna have children?
Dharma: Yeah, unless you wanna have 'em.