Continuity mistake: In the shot after Robin Williams has been sprayed to wash off the crap from the RV he is bone dry after the spraying is complete. They only show his upper body at this point but the spraying would have been over his entire body.
Continuity mistake: When bike riding Bob grabs hold of the Gornicke bus ladder, his hands grip different rungs between multiple shots. (01:22:25)
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: When Bob has difficulty with his seat belt at the start of the road trip, the side-view mirrors have a translucent finish, just as in other shots throughout the film; however, the mirrors' surfaces are normal in the rest of the shots. Deliberately done to obscure the reflection of the crew. (00:13:20)
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)
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)
Factual error: When the family is beginning their trip, Bob has difficulty putting the RV in gear. We hear gears grinding despite the fact that the vehicle obviously has an automatic transmission (as evidenced by the column shifter). Automatic transmissions do not contain the same type of gearbox as manual transmissions, and it is impossible for an automatic to create a gear-grinding noise. (00:13:30)
Revealing mistake: When Bob is on the bus' roof there are interior shots of the bus and all its right side (viewer's left) sliding metal framed windows are visible and intact. After Travis stops short, in the following exterior shots four of the double sliding windows have been deliberately removed from their tracks, so the camera's view of the kids is unobstructed. (01:23:10)
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)
Continuity mistake: As Bob hangs onto the Gornicke ladder, when the bicycle falls in the first shot it falls to its left; however, in the next shot the bicycle falls to its right. (01:22:25)
Revealing mistake: When Bob hangs upside down on the Gornicke windshield, in the shot facing the bus as he begins to fall, we can see the driver's and front passenger's seats and Travis, his wife, and Jamie are all gone. Of course they are back in the following shot. (Only visible on fullscreen DVD.) (01:23:15)
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 the RV speeds along at 12 MPH behind the tractor, the shadows keep changing. In the interior shot the shadows are cast to the right of the tractor, but in the exterior shot, as the RV passes, the long shadows are cast to the left of the tractor. (00:40:30)
Continuity mistake: After the Big Rolling Turd has rolled backwards over the grocery carts, in the shot of the RV heading down the highway the back center window curtain is hardly open. In the following interior shots, as they sing, the entire curtain is open, but in the last exterior shot it is hardly open again. (00:17:15)
Revealing mistake: The Munro's RV has a large pop-out (slide-out) on its left side, behind the driver. When the pop-out is closed one side wall should be directly behind the driver's seat, but that wall is gone - it has been deliberately removed. As a side note, when the Munros rush to leave before Mary Jo Gornicke reaches them, that wall (with a small window) is seen in the exterior shot, as it slides in. (00:19:15 - 00:39:30)
Continuity mistake: In the scene when Bob is on top of the Gornecke's RV, and they stop suddenly, you can see that the gates of the Alpine beverages company are a distance away. However when they walk around the front of the bus in the next shot, it is as though they pulled up right in front of them. (01:19:50)
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 Gornickes get ready to sing for the Munros, Earl gives Billy the red kazoo, which is seen in the front shots, but in the side shots Billy holds nothing. (00:33:55)
Continuity mistake: When Mary Jo begins walking to the RV at 6:00 AM, Bob and Carl remove the tire blocks outside, while Jamie closes the "stupid pop-out thing" inside. In the exterior shot, as it slides in, Bob is sitting with his hand on the steering wheel - though it isn't until two shots later that Bob actually gets back to the driver's seat. (00:39:25)
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)
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