Continuity mistake: When the RV is stuck behind the slow moving tractor, as the RV tries to pass, in some shots there is only a single yellow line and in some there are double lines, it goes back and forth. (00:40:30)
Continuity mistake: When Bob passes the tractor, in the exterior shot, as he just misses the truck the back window curtain is shut, yet, in the previous and following interior shots, that curtain is wide open. (00:41:05)
Continuity mistake: When Earl gives Cassie the list of places that sell organic health food, in the close-up she holds the papers with her right hand at the top and left hand at the bottom. However, in the next shot it's the opposite way, her right hand is at the bottom and left at the top. (00:44:05)
Continuity mistake: Bob tosses the stink bomb canister through the open door, towards the back of the RV, but the smoke cloud appears in two different areas; it expands at the sink window and at the front passenger window, with clear air seen in between through the door. (00:50:15)
Continuity mistake: After all four go sliding down the mud, at the bar when Jamie takes the knotted cherry stem out of her mouth to show Carl, the stem differs in the next close-up. (00:52:40)
Continuity mistake: When the Gornickes catch up with the RV, its shadow is cast to its right, but after Cassie tackles Carl to the ground, there's an exterior shot of the RV and bus as they both cast long shadows to their left. This drastic change in shadows continues in following shots. (00:57:00)
Continuity mistake: When Mary Jo hangs out the bus window shouting, "Pull over..." not only does her hair go from windblown and messy to neat between shots, her pink scarf/headband disappears and reappears. (00:57:40)
Continuity mistake: When the Gornicke kids point paint ball guns at the Munro RV, Jamie screams, and when Bob dives to the floor his arm rest goes down and up between shots, while he is ducking. (00:58:00)
Visible crew/equipment: On the highway, after the Gornickes were unsuccessful at returning the laptop, when the RV takes the exit in the rear shot the crew's location set lights are reflected on the RV's surface. (00:58:00)
Revealing mistake: When Bob throws pitches to Carl while he barbecues, the close-up of the grill shows Bob's arm holding the tongs as he fiddles with the food. Problem is, it is not Robin William's notoriously hairy arm and hand in the close-up. Things on the grill differ between shots as well. (01:01:10)
Continuity mistake: When Bob drives up Diablo Pass and ends up teetering on the mountain, his seatbelt is strapped across his chest. After the first close-up of the speedometer, his seatbelt is off as his foot steps on the accelerator, but after second close-up of the speedometer his seatbelt is still on. (01:09:45)
Revealing mistake: When the RV teeters on the mountaintop, Bob opens the RV door and then swings out, but the three automatic stairs below the doorway do not engage - deliberately done for the humor. (01:10:00)
Continuity mistake: When Bob drives up Diablo Pass and also when the RV teeters on the mountain, in the exterior shots the back curtains are closed, but in the interior shots they are wide open. (01:10:40)
Continuity mistake: When Bob drives up Diablo Pass and also when the RV teeters on the mountain, in the exterior shots the back curtains are closed, but in the interior shots they are wide open. (01:10:40)
Continuity mistake: When Bob is chasing the Gornickes on the bicycle, the bus turns right onto the highway. In the next shot, it is turning left. (01:12:00)
Continuity mistake: When Bob is hanging onto the RV's wiper blades, as it nears the campsite, in the last close-up his shirt is completely dry, but in the first shot just as he is thrown backwards, suddenly there are numerous sweat stains on his shirt. (01:12:30)
Continuity mistake: When Bob is thrown to the ground, and the RV drives over him, in the overhead shot the tire tracks on the dirt run the entire length of his body. In the next shot, however, the tire tracks only begin beside Bob's head. (01:12:40)
Revealing mistake: After the RV rolls over Bob, in the overhead shot as he lies on the ground, there are two tire tracks - one to Bob's left and another to his right. Problem is that the RV has four rear tires, which actually should have left the imprint of four tire tracks. (01:12:40)
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)
Continuity mistake: When the RV rolls into the lake, the side-view mirror is intact. Next shot, as Bob rushes to rescue the sinking RV, the entire side-view mirror is suddenly gone. Later, after they pulled the RV from the lake, that side-view mirror is intact again. (01:15:35 - 01:29:55)
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