Other mistake: The opening credits for season 5 show June coming out of the front door with a pitcher of what looks like iced tea, and calling for Ward, Wally and Beaver who are all working outside. But the door opens by itself as she comes out, and then closes by itself behind her. If the entire family is outside, who opened and closed the door?
Leave It To Beaver (1957)
1 other mistake in Season 5 generally
Starring: Barbara Billingsley, Hugh Beaumont, Jerry Mathers, Tony Dow
Wally's Practical Joke - S6-E35
Visible crew/equipment: When Eddie Haskell comes over to scheme getting back at Lumpy, just as Eddie, Wally and Beaver are heading up the stairs, a mike boom is visible in the upper left corner.
Eddie Haskell: Look Sam, if you can make the other guy feel like a goon first, then you don't feel like so much of a goon.
Wally Cleaver: I don't get that.
Eddie Haskell: Of course you don't. That's because you never went to kindergarten with a home permanent.
Captain Jack - S1-E3
Trivia: The gentleman at the alligator farm is the same one who plays Uncle Billy later on.