Marsha, Queen of Diamonds (1) - S2-E23
Continuity mistake: After Batman has been hit by Marsha's love dart, when Robin pulls the dart out and then begs Batman to resist it, in these semi closeups note Burt Ward's uncovered forearm with his still-healing burn wound. Then, while the Dynamic Duo fight Marsha's sabre wielding goons, Marsha hits Robin with another one of her darts and orders him to attack Batman. When this happens, Burt Ward's forearm now has a compression bandage around the wound. (00:13:55)
Continuity mistake: When Davy is telling Mike and Peter that Otto and Sigmund are trying to kill Bettina, the sandwich Mike has switches from his left hand to his right hand in a split second.
Continuity mistake: In "The Unsinkable Mr. French" (season 5), the amount of whipped cream on Mr. French's jacket increases as he's getting up from the couch. (00:23:00)
Goodbye, Hello, Goodbye - S1-E2
Continuity mistake: In Season 1, Episode 2 ("Goodbye, Hello, Goodbye"), just before Ann Marie and the doorman enter her new apartment with 2 suitcases and a handbag, a wider view of her apartment shows the same 2 suitcases and handbag sitting inside by the door. (00:03:34)