Continuity mistake: When Bob speaks to the entire Alpine company, with the Gornickes watching, all their shadows move 180° to their right from the start of Bob's speech to Todd's flip. (01:26:45)
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)
Revealing mistake: When the Munros begin their trip, as Bob makes the sharp right turn the RV's pop-out begins to open directly behind him, and its left wall is missing - we can actually see the RV's window at the opposite side, through the opening. (00:15:25)
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)
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)
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: After the Big Rolling Turd runs over the grocery carts, Bob's shirt goes from having four buttons buttoned up, then to five, back to four, then back to five again. (00:16:20)
Continuity mistake: At the start of the road trip, when Bob tries to maneuver and turn the RV around on their street, the interior shots looking out and the exterior shots do not match up in consecutive shots, regarding the homes and gardens, etc that are seen. (00:13:45)
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)
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)
Visible crew/equipment: When everyone is singing their own song (except Robin Williams), the last shot of this scene shows the back of the RV. As the camera pans down, you can see several cars reflected in the window, one of which is the crew's truck with the camera crane erected above it. (00:18:35)
Audio problem: After reaching Alpine via the Gornicke bus, when Bob says, "Some of my behavior on this trip might be misconstrued as an insult," Bob's mouth/jaw does not match most of his words. (01:25:10)
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 the thoughtful gentleman offers Cassie the 'vegetarian' organ stew things on the table disappear, reappear and change between shots, such as Earl's plate, the flowers, etc. (More visible on fullscreen DVD.) (00:32:50)
Continuity mistake: After Travis hoses the turd off Bob, when Billy remarks that 'Ernest Goes to Jail' is funny, the boy's left front tooth (viewer's right) is fully grown in; however, that evening, after dinner, Billy's tooth is barely halfway grown in. (00:28:55 - 00:37:00)
Continuity mistake: After Jamie pinches Carl's ear because he spills their destination, when Mary Jo walks toward the Munros, Billy's back faces the camera as he stands on the ground, away from the bus. However, in the next shot Billy faces the camera as he stands on the stool while leaning on the bus. (00:35:10)
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)
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: In the RV, when Bob turns around to glance at Cassie after the dishes fall on her, in the first shot his arm rest is up (look beside his right shoulder) as he faces her, but when he says, "My bad," the arm rest is down. (00:15:30)
Continuity mistake: When the Munros first hitch a ride with the Gornickes, after Bob takes off on the bicycle, as Cassie questions Earl the calculator repeatedly disappears, then reappears, and the books, etc change between shots. (01:18:55)
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