Corrected entry: In the opening scene where Clark and the two guys in the pickup are racing, Clark pulls under a 18-wheeler. In the close up shots, you can see the truck's tyres from under the truck, but in the far away shots, you can see the safety bars that were put under the truck for the stunt driver so he wouldn't ride up under the truck.
Corrected entry: Throughout the movie there is an Advent Calendar that is opened from time to time, revealing what day of December it is. However, in the scene where the grandmothers are sitting in the den and one of them is decorating a gingerbread house, they are watching the Macy's Thanksgiving Day parade, which takes place in November.
Corrected entry: We later learn that Eddie's RV makes a lot of noise when driven. How did they ever make it into the Griswald driveway without anyone noticing when they first arrive?