Continuity mistake: In the scene where Kenny feels he's been bit by a spider on his privates and run off the bus with everyone following after him. Kenny then pulls down his pants so they can look at it. Throughout these scenes, his pants are supposed to be pulled down. Right at the moment Kenny faints from the bite, you can see that his pants are pulled up and buttoned.
Continuity mistake: In the scene where Jennifer Aniston has finished giving a striptease and the Mexican Drug Lord, Pablo Chacon falls from the chair because of the steam on his face, he is shown sitting in front of the RV, but he falls right on to it. Then when Will Poulter drives the RV in reverse, Matt Willig is shown colliding with it, but Pablo Chacon is out of the picture. (01:18:10 - 01:18:50)
Factual error: When the Millers' RV breaks down and it gets towed by the Fitzgeralds' RV, the two are connected by a tow rope. There is no one in the Millers' RV steering or working the brakes. The RVs would crash into each other the first time the front one slows down, and the Millers' RV would not steer properly to follow the Fitzgerald's. Also, when we see in the Fitzgeralds' side mirrors, we don't see the Millers' RV being towed.
Continuity mistake: When they are arguing by the RV about getting paid, Casey doesn't have her purse, but as she goes into the RV to "grab" it, her purse is on her left shoulder as she enters the RV, but isn't there in the frames right before going into RV.
Continuity mistake: At the end when Rose is showing David the video of Kenny, only 8 seconds have played. The shot changes to Rose and David for less than 3 continuous seconds and then back to the video. However, the timer now shows 40 seconds have played.
Revealing mistake: When Kenny Rossmore starts the RV to get away from Pablo Chacon and One-Eye, you can see the dashboard of the RV and the temperature gauge shows the engine is already warm, despite supposedly being started from cold. (01:18:40)
Continuity mistake: In the scene near the end where Pablo Chacon is holding a gun to Melissa's head and telling Don Fitzgerald to give him the gun and mug, we see the gun pointed towards Melissa for the front shot, but in the next shot where we see Don giving Chacon his gun and mug, the gun is pointed towards the ground. (01:44:10)
Continuity mistake: When the Millers and Fitzgeralds are playing Pictionary, Melissa draws a little stick figure with a hat, the camera cuts to Kenny for his line, when they cut back to Melissa the stick figure with the hat is missing. In fact all the drawings are slightly different. (00:57:25)
Other mistake: When Sarah and Casey learn they're only getting a small portion of the money, Kenny says "Wait, you guys are getting paid?" However, he was there when David agreed to pay Casey $1000. He knew she was getting paid.
Answer: Don.
No, he was driving Fitzgerald's RV.