Other mistake: After Todd phones Bob and tells him about the rinkle-dinkle regarding Larry's request, when the Munros sing about the Rolling Turd, in the close-up, as the RV drives past the camera, the sideview mirror is deliberately turned all the way around so as not to see the crew's reflection. This also occurs when Bob asks the Trooper about the traffic jam around Mt. Watson. (01:14:00)
Other mistake: In the scene where Bob is trying to get reception on his pocket PC, he is on a rock and the pocket PC beeps, indicating that there is no signal. But when it goes to a closeup of the pocket PC, you can see in the top left hand corner that the signal is full.
Answer: In the world of "make believe", they used "movie magic" to zap the RV out of the water and on to dry land - with no mechanical issues resulting from being submerged. In the real world, someone called a tow truck - perhaps AAA - and the RV was pulled out of the water and it suffered water damage and needed some repairs. This movie was presented as being "real life." Bob left on a bicycle to "try to find help." Near the end of the movie, Carl said that the RV "spent two days under water and they had to fish it out." He didn't say who "they" were. A fishing pole would not be strong enough to reel in a large RV, so I think it is safe to conclude that a tow truck was used to pull the RV out of the lake.
KeyZOid
It should be noted that "fish it out" is a common phrase to mean pull or take out, especially after searching. When people use the term, they're never taking about using a fishing pole. But often when people post questions like this, they're asking for an in-film explanation in case they missed (or didn't understand) something. If no in-film explanation was given, a reasonable speculation can be given. You don't need to remind people the movie is a movie. If the in/film explanation is uncharacteristic to real life, then one can point out that in real life it wouldn't happen that way.
Bishop73
It was meant to be ironic.
KeyZOid
There was no irony, but this isn't the forum for irony anyways.
Bishop73
I guess I failed miserably... but wasn't the original question rhetorical?
KeyZOid