Mark Metcalf's character, Colonel Neidermeyer, is a reprise of his role in Animal House, despite the end of that movie stating that Neidermeyer was killed by his own troops in Vietnam. However, this can be explained as just a subtle nod at Metcalf's earlier role (the only way you can even see what name is on the name tag is if you freeze the movie when the tag is close to the camera).
When the Stupids set off to Warehouse 21, they leave when the sun is up. You see their car pass under a bridge with a sign reading "Warehouse 21 5 Miles" but when they arrive at the warehouse, it is the dead of night.