Dear Mrs. Petrie, Your Husband is in Jail - S3-E28
Character mistake: Rob is telling Laura why he's in jail. He says "Monica Doorwell! She must be Millie and Jerry's babysitter." The babysitter's last name is "Darwell". (00:02:00 - 00:04:00)

Starring: Dick Van Dyke, Mary Tyler Moore, Morey Amsterdam, Larry Mathews, Rose Marie
Dear Mrs. Petrie, Your Husband is in Jail - S3-E28
Character mistake: Rob is telling Laura why he's in jail. He says "Monica Doorwell! She must be Millie and Jerry's babysitter." The babysitter's last name is "Darwell". (00:02:00 - 00:04:00)
Sally and the Lab Technician - S1-E3
Continuity mistake: When Jamie Farr the "Snappy Service" guy comes in and gives everyone their coffee Buddy throws a straw into the straw cup, but it falls down on the floor then vanishes, never to be seen again.
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.