Continuity mistake: When we first see Richie at the beginning of the episode he has extremely dark "bruises" all over his hands, arms and face. But by the end of this episode all the bruises are gone except for 1 which is on his face below his left eye (on our right). Bruises do not just vanish in 2 or 3 days if they are that bad.
The Dick Van Dyke Show (1961)
1 continuity mistake in Girls Will Be Boys - chronological order
Starring: Dick Van Dyke, Mary Tyler Moore, Morey Amsterdam, Larry Mathews, Rose Marie
Your Home Sweet Home is My Home Sweet Home - S4-E25
Continuity mistake: The Petrie house (where Rob and Laura, Jerry and Millie are standing together bickering) is completely different from the episode "Where Did I Come From?" and a few others.
Rob Petrie: At least I'll prove one thing tonight: Television writers marry the prettiest girls.
Trivia: During the fourth season, actress Rose Marie suffered the tragic loss of her husband to whom she had been married for 20 years. Amidst her mourning, Marie felt that the grief and pain of loss was too much to bear and wanted to leave the show entirely, just before the fifth and final season. John Rich, one of the show's directors, was there to console her and convince her to come back and finish out the remainder of the show.