When Joe drives through the security gate, he clearly breaks the crossing arm but the next angle shows it intact.
Joe's carnival girlfriend pulls her shirt's shoulder strap down twice the same scene without putting them back up.
In the beginning we see Joe Dirt pulling into the radio station in the car he picked up before taking Jill out on a date, but we later see that he abandoned that car on his way to Silvertown when Robbie reads him the note.
When Joe Dirt is standing outside his parent's abandoned house at night there is a porch light on.
When Joe and Robby begin race, Joe's car kicks up rocks and Joe takes off. View from our angle shows Robby's windshield intact. Next, from Robby's perspective, windshield damaged in several places.
The Slant-6 is a Chrysler automobile engine, known within Chrysler as the G-engine. It is an inline-6 piston engine designed such that the cylinders are inclined at a 30-degree angle from vertical. GM Trans-Am would not be using a Chrysler engine.
During one scene in a chemistry class, a student identifies the gas resulting from an experiment gone wrong as "poisonous mustard gas." The symptom of those exposed to the gas (immediate loss of consciousness) is inconsistent with the actual physiological effects of mustard gas (irritation of exposed tissues with delayed presentation).
Joe's parents can be arrested for child abandonment. As they acted careless when Joe found them.
Cafeteria Scene: When Joe goes to clean up the puke pile in the cafeteria, he clearly flinches before being hit with the first 2 hot dogs; he clearly knew they were coming.
When Joe is doing his alligator show, the wiring harness that picks him up when he is in the alligator's mouth is visible.
When Joe is standing on the bridge, cop lassos him with a bungee cord. As he falls, the single rope appears to become three or four.
When Joe walks out of the radio station there is a guy there in the crowd with the exact same hair cut as Joe even though he hadn't been seen by anyone outside the studio before that point.
The Rambler Wagon was represented to have a 258 Six engine. The 258 did not appear until the 1972 model year, and there were no Ramblers then. The entire model line up was under the AMC badge since 1970. Were the car a Rambler wagon with a three on the tree, it would have been either a Rebel, with a 232 Six engine, or an American with either a 199 or 232 Six engine.
When the alligator goes to throw Joe, we can see one of the wires just after he lands on the ground.
When Joe is talking to the man at the car dealership about the old Rambler wagon his parents owned, the man tells him that car came with a "6cyl, automatic with three on the tree" A three on the tree is a manual transmission not an automatic
The car he bought from the old woman he calls a Road Runner. Its actually a GTX, a 1967. Road Runners came out in 1968, and look nothing like a 67 GTX.
After Joe gets blown away in the balloon, he says that he got blown to North Dakota, but the red dashed line shows him going to South Dakota.
When Buffalo Bob gives Joe an Auto Trader he hands him the red copy of an Auto Trader, which is cars priced $5000 or less. He then speaks of a car priced at $14,000 which would have not been printed in that version.
Joe Dirt maintains his parents car was a 1968 Rambler Wagon made by AMC. When he arrives at his parents trailer park he sees his parents old car in the driveway but the car shown is a 1959 Rambler Super Wagon by AMC.