Continuity mistake: When Andy first charges at Pee-wee with the dinosaur bone, he swings it over his left shoulder. In the next shot he repeats the same action (albeit slightly differently). (00:49:20)
Revealing mistake: After the bar scene where Pee Wee leaves riding the motorcycle, we can see it's a stuntman, given the different physique of having wider shoulders and a fuller head of hair than that of Pee Wee.
Other mistake: The security footage that Terry shows of Pee Wee going through the Godzilla set is simply a black and white version of the same footage we see as movie watchers of the film, not from the camera being used to shoot the movie.
Continuity mistake: In front of the AM radio station downtown where Pee-Wee and Dottie are busy posting a $10,000 reward sign, the amount of red tape applied to the sign, especially the top, changes between shots. (00:25:40)
Other mistake: Just before Jack and Pee-Wee start singing in the rail car, their train passes by some empty farmland. Pay particular attention to the buildings on the horizon, though. After a few songs, Pee-Wee can't take it anymore and decides to cover his ears and bail out - but where he lands is the very same location described before the singing began (note the exact same buildings and distance to them, which hasn't changed at all), as if the train didn't cover any ground. (00:51:15 - 00:52:05)
Continuity mistake: After Mickey and Pee-Wee evade the highway patrolman, Mickey takes a good look at Pee-Wee in the outfit and smiles. Before the scene cuts away, you can see how the convertible is missing its rear-view mirror. Soon Pee-Wee sends the car over a cliff's ledge and, as they're screaming together on the way down, a rear-view mirror is hanging from the windshield all of a sudden. But once the car hits ground, the mirror is no longer there. (00:37:40 - 00:39:00)
Answer: It was some sort of gag gum (popular in the past) that either had hot pepper/cinnamon or simply tasted terrible.
Brian Katcher