Other mistake: In the scene where Don arrives at Dick's 'party', he looks at his non-existent watch. (00:13:25)
Continuity mistake: In the scene where the F.B.I. storm Dick's house, Charlotte's sleeves change length (i.e. being pulled up or like normal) throughout the entire scene. (00:20:00 - 00:20:30)
Continuity mistake: Mary's glass of wine goes from being almost empty to about half full during her conversation with Charlotte. In the same scene Charlotte goes to put the bottle down but in the next shot she is still holding it.
Dick's Big Giant Headache (1) - S4-E23
Continuity mistake: After Harry eats the egg, the lid is still up. When Vicki walks in, the lid is down.
Dick's Big Giant Headache (2) - S4-E24
Revealing mistake: When Stone is about to drop the bowl of punch on Alissa from behind her, you can see she braces herself for it before he starts pouring it on her (she knows it's about to come when he says "Oops"). (00:13:05)
Episode I: the Baby Menace (3) - S5-E1
Revealing mistake: When Tommy is asking if everyone remembers which baby came from which incubator, you can see the baby he his holding in his left arm is just a doll. (00:09:10)
Continuity mistake: Dick's plot in this episode is that he learns about the concept of tipping. However, the season 3 episode "Eleven Angry Men and One Dick" showed that Dick was already familiar with the concept of tipping when he tipped a bailiff during a jury selection process.
Dick Puts the Id in Cupid - S5-E11
Other mistake: While talking to his therapist, Dick tells her that one of the mishaps that he caused in his relationship with Mary was showing up to a fundraiser naked. While true, this doesn't happen until Episode 13 (Rutherford Beauty) - two episodes later. This was due to the fact that most of Season 5 was aired out of production order.
Suggested correction: The show was produced in the right order, so this isn't a mistake. Being aired out of order isn't a mistake of the show. It should be noted that for each of the 6 season, episodes were constantly aired out of order.
Dick Puts the Id in Cupid - S5-E11
Factual error: At the police station, in lock up, there's a paper on the bulletin board with a phone number "1-800-VICTIM" An 800 number should have 7 letters/numbers instead of just 6.
Continuity mistake: The devil horns, mustache and goatee that Tommy spray paints on the picture of Harry change appearance between shots. (00:16:40 - 00:17:15)
Continuity mistake: When Caryn is on the desk, her back is to the class. After the pledge, when Dick says "never mind" and the camera angle changes, she's now facing the class.
Dick's Ark - S6-E12
Character mistake: Sally tells Dick that he's jealous of her gig as a weather girl because he's never been on TV. However, Dick did appear on TV as a panellist on a talk show highlighting Dr. Strudwick's physics book in the season 4 episode Dick vs. Strudwick. Dick ended up turning the show into a Jerry Springer-like fiasco, and Sally even attended the taping. (00:10:40)
Dick Soup for the Soul - S6-E16
Audio problem: When Tommy is talking about how he recruited Sally to help him get into the fraternity, but has gone mad with power, at one point it switches to a wide shot and you can see his mouth isn't moving. (00:19:28)
Mary Loves Scoochie (1) - S6-E17
Revealing mistake: The sword fight between Dick and the Black Knight was sped up in order to make their movements look more competent. Note the extras in the background moving unusually fast.