Revealing mistake: After Pee-Wee tears through a Godzilla production in the Warner Bros. studios with his bike, he exits the stage, ending up on an alley where he turns left to evade the props and security guards on his tail - one of which has a motorbike. On the pavement beneath him is a curved skid mark from a previous take, not unlike the one left behind by the motorbike seconds later.
Revealing mistake: Throughout the studio scene where Pee Wee is shot from the front being chased by security, the fact that his bike is on a rig can be seen by how rigid the bike is when he pedals it and it doesn't move side to side like it does when he's riding it freely in all the other shots.
Revealing mistake: The entire snack bar cartoon sequence shot at the drive-in theater during the world premiere of "Pee-Wee's Big Adventure" is actually a montage of different shots patched together, and it almost looks completely seamless until you focus in on the car farthest right. Notice how the passengers change positions every time the shot changes on the drive-in screen.
Revealing mistake: In the scene where Pee-Wee is face to face with Professor Tanaka asking for Francis' whereabouts, the background behind Pee-Wee turns into an obvious painting on a set between shots. Notice how all sunlight and wind vanishes when he shouts "Where are they hosing him down?"