Factual error: This happens during the scene when Harry and Lloyd offer the little boy 5 dollars to get them slushies. This movie is set in the 80's but notice the $5 he gives him. It is the newer issued $5 that came out in the 90's.
Factual error: When the guys are playing "it" in the Big A store, you can see Dasani and Mountain Dew Livewire - drinks that have only been around a few weeks/years.
Factual error: In the scene where Lloyd puts on a record on over the loud speaker to get ready for school in the morning, it plays Ice Ice Baby. This song was first released in 1990, whereas the film's set in the 80's.
Factual error: Throughout the movie, Lloyd and Harry often drink Slushees. However, Slushee was not a company until 1996.
Factual error: The Big A store sells beer and wine. In Rhode Island, it is not allowed for convenience stores to sell alcohol.
Factual error: In the scene where the principal is in the car asking about the chest. They pass by a house with a 1990's Chevrolet Suburban.
Answer: Because Harry and Lloyd had poured gasoline all over the car as well as let the pump keep running when they left. So when the hot ash of the store clerk's cigarette hit the gas fumes, it caused the explosion.
Bishop73