The Illusion of the Lethal Playthings - S1-E20
Revealing mistake: The "remote control" model plane lands and sneaks through some bushes to spy on Blake. You can see the filament line pulling it. And the picture it sends the bad guys with its mini-camera not only zooms in (unlikely technology in 1973), it also delivers an unobstructed view when the plane is sitting in foliage that should block part of the shot. (00:21:50)
The Illusion of the Lethal Playthings - S1-E20
Character mistake: A toy company would surely know better: the sign outside the toy factory misspells "Pinocchio" with only one C instead of two. (00:25:20)