A life-long fan of camping, Jeff Daniels has owned an RV for years. According to a Detroit radio interview, his RV driving lessons for the movie were quickly canceled when he arrived on location in his personal recreational vehicle.
Carly Schroeder was originally cast as Cassie Munro but had to drop out of the film due to scheduling conflicts with Firewall (2006). The role then went to Joanna 'JoJo' Levesque.
The Munro RV is a Forest River, Georgetown 359 TS. Five of them were purchased, plus a sixth which was ordered in pieces and assembled in a way that allowed hydraulic rams to raise and lower it out of the lake. Two were fitted with special suspension hydraulics to handle some of the extreme driving moments. Two of them are the ones that the Munros are seen living and driving in. The 5th was dubbed "Wild Thing" and was fully functional.
When Bob Monroe and the RV is stuck at the top of a mountain road with all wheels off the ground and he guns the gas pedal the RPM goes up to 6000 rpm yet the speedometer is still at zero .. when you have transmission in gear and wheels turn -regardless of ground contact or not- the speedometer will still register your speed through rotation of rear wheels thru the transmission which is in Gear.
Early in the movie there is a scene with Bob speaking with his boss Todd. When the camera is focused on Bob, the back of Todd's head can be seen. In that shot Todd's words don't match up with the motions his jaw is seen making.