Averted in Johnny Knoxville's case, THRICE, first in the first movie during the "Rent-A-Car Demolition Derby" where one of the cars crashed into his, having it's wheel smash through the windshield, inches away from Knoxville's face. The second time, later in the first film during the "Golf Cart Antics" when a golf cart with Knoxville and Dunn (who was driving) flipped over a fiberglass statue and got wrecked. Knoxville actually could have broken his neck from it. The third was in Number Two in the "Big Red Rocket" skit, the rocket he was gonna fly up into the air and into a lake ended up misfiring, exploding with him on it. It exploded on one part just inches away from his stomach. Then he tried it again, that time it worked.
Executive Meddling: Among other things: after season one MTV handed Knoxville and company a list of things that they were not allowed to do, as far as content goes. Similarly, when Sen. Joseph Lieberman tried to get the show banned from airing, MTV caved like cowards, pulling all reruns of the series (which was in season two by that point) and forcing Knoxville to revise the show's warning so as to read it out loud to viewers.
Lieberman's actions also squashed plans for a "Jackass: Too Hot For TV" video release.
Keep Circulating the Tapes: The only full, uncut episode available on DVD is the hour long Gumball Rally episode, which is only available on the bonus disc for a box set released. All three seasons are only available as a series of "Best Of..." compilations (with V2 and V3 having two releases, with the re-release having extra sketches added) and a "Lost Tape" compilation, which has all of the opening/ending sequences and the MIA sketches that didn't make the previous three DVDs.
Further adding to the mix, the season one "best of..." set was delayed for about 6 years due to feuding between the Jackass crew and MTV; while Knoxville and company have full control over content for the DVD releases, MTV outright refused to let them release season one on DVD due to their not wanting to let the gang wanting to release the Big Brother magazine sketches uncensored. Knoxville and company finally caved, meaning that you'll have to track down the original Big Brother magazine VHS tapes for the full version of the self-defense test sketch.
What Could Have Been: MTV (who owns the rights to the name "Jackass") seriously considered making a Season 4 with all-new cast members and even put out a teaser commercial in the 2002 VMA Awards. Thankfully they didn't when reaction to the news was extremely negative.
Jackass: Too Hot For TV, which got killed when Lieberman started making noise against the show.
Bam's uncle was to be in Jackass 2 a great deal (you can see the original Lambo-tooth-pull in the trailer used against him), but a judge ordered all scenes relevant to him pulled off after being convicted of child molestation.
The Terror Taxi very nearly got here — they nearly got stopped by police twice, and Jay Chandrasekhar kept going off the rails (the police were told about the skit, but they still set up a damn roadblock), and two bystanders called the cops.
They were also about to attach squibs to the fake dynamite to scare Ehren more, but the Fire Marshall told them they had to more or less ruin the prank.