Continuity mistake: When Gary and Larry catch up with Bob, the trees and snow surrounding the two cars differ after the RV destroys the vehicles; also, note the tree tops. (01:31:50)
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: At the very end when the Munroe family gets stopped by the police, they walk directly behind the RV. A moment later when the RV rolls down the hill (and runs over the police car) it is facing toward them. For it to do this it would have to run over them.
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.
Continuity mistake: In the RV, Jamie puts stacks of dishes away in the overhead cabinet - second from right, when Cassie moves Carl off the couch. When Bob makes the sharp right turn, the dishes pour out of the overhead cabinets, but the ones that come out of the second cabinet are not the same dishes that Jamie put away. (00:12:20 - 00:15:00)
Continuity mistake: When Bob speaks to his coworkers at his office, Bob says, "Bring jewelry," and his glass is nearly empty, but a couple of shots later, as he still sips his straw, the glass actually has more liquid now. (Difference only visible on fullscreen DVD.) (00:08:45)
Audio problem: After the RV rolls into the lake, Jamie asks, "What meeting?" then Bob answers, "The Alpine merger," and in the next shot facing Jamie, Bob turns his head as he is still talking, though nothing is heard. (01:16:10)
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)
Revealing mistake: When Bob is riding the pushbike down the steep hill to get to his family and the Gornickes at the bottom, in some shots you can blatantly tell that a stunt double that looks nothing like Robin Williams is riding the bike. The stuntman is also visible later when Bob is on the roof of the Gornickes' bus.
Continuity mistake: Just forward of the right rear wheelwell, a small dent disappears and reappears throughout the movie.
Audio problem: The Gornickes and Munro family pull out of the gas station in their bus-type vehicle while Bob is coming down the hill on the bike. There is a "ding ding" sound typical of full service gas stations or auto repair places. These require the long black wires to trigger when tires run over them but no wire is visible.
Factual error: There is no way Bob would manage to get the RV as stuck as it was going up the Diablo road. Just as the top of the road had made contact with the undercarriage the RV would have stopped moving.
Deliberate mistake: At the end, there is no way that the RV managed to roll over and flatten the vehicles in its path.
Continuity mistake: When they arrive at a campsite to take in the view of the lake that Bob saw with his family as a kid they leave the door to the RV open with the stairs down. After some dialogue the RV rolls into the lake with the stairs up and the door closed.
Continuity mistake: When Jamie and Bob are sleeping in their bed, the things from the bedside table have been changed.
Continuity mistake: After Bob comes home with the RV, when he and Jamie walk into the kitchen there is a butcher block cutting board laden with items, at the edge of the counter. However, when they speak beside that island counter the cutting board is gone. (Even more noticeable on fullscreen DVD.) (00:10:20)
Continuity mistake: When the Munros pick up Gretchen at her house, many shadows are cast on the lawn. Later, when they drop her off, the shadows are identical - they have not changed a bit. (00:03:20 - 00:05:25)
Character mistake: When Bob Munro (Robin Williams) is behind the tractor, the speedometer shows that it is below 10mph. He then states that they are going twelve. How could he if they didn't reach 10mph yet?
Visible crew/equipment: When the Gornickes and the Munros are eating outside at the RV park, you can see a crewmember reflected on the Gornicke bus.
Visible crew/equipment: After the State Trooper stops the Munros, when Gary and Larry speak to Bob the reflector screen is clearly reflected in Larry's eyeglasses. (01:31:50)
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