Character mistake: Rob is telling Laura about how Buddy and Sally work he says "Sally is the only one who can type with all her fingers." Yet Rob can type with all his fingers and doesn't say anything about that.
The Man from My Uncle - S5-E27
Continuity mistake: When Rob and Harry are in Richie's room, it's bright and sunny outside. Six seconds later, they are in the living room, and it's pitch black outside.
The Man from My Uncle - S5-E27
Factual error: The Government Agent says "we want to use your house for base operation for looking at the house across the street. Rob says "Jerry helper!" yet Jerry lives on the same side of the street (closest to the den, across from Rob's bedroom). Someone has their houses mixed up.
You Ought to Be in Pictures - S5-E28
Deliberate mistake: The movie director tells everyone "ACTION!" Yet Rob stands outside the door and doesn't come in, then he says "uh...action?" Then Rob pokes his head in and asks Leslie "Did you say something?" In "Somebody Has to Play Cleopatra" Rob is the director of the play. He says "Action!" and then Harry (Bob Crane) does not come in on cue several times. Rob also calls Leslie "Liz". (00:15:35 - 00:16:20)
Love Thy Other Neighbor - S5-E29
Other mistake: Laura tells Rob that Jerry is fixing the fence. Then all of a sudden this banging that sounds like an iron hammer and chisel on cement starts up. If Jerry was actually fixing the fence it would have been the whole time, right when Rib got into the kitchen, not right after Laura told Rob that Jerry was working on the fence.
Continuity mistake: Laura is reading the name of Rob's book "Unimportant Life of Robert F. Petrie" yet in "Fifty-Two, Forty-Five or Work" Rob said his name was "Robert Simpson Petrie"
Revealing mistake: Millie (in Rob's dream) tells Jerry (Doc) that "Big Bad Brady is already dead" yet we see that Brady is up there trying to not move, laugh or breathe. He's still alive if his stomach is still going and moving the whole time. Also when he aims his pistol at Rob, he's aiming it at Rob's hat. Not at Rob's arm. Which is where Rob said he got "shot".