Other mistake: In one of the opening scenes where the boys ride to the baseball game, the fishermen they pass make a rude comment towards them. In response, you hear Joe ring his bicycle bell and see them flip the men off. The bicycle has no bell.
Other mistake: When Robert Downey Jr. lowers the helicopter onto the freeway to yell at the truck driver, he is very close to the truck driver, so close that the truck driver can even hit the helicopter. Why does a long haired man standing underneath a helicopter not have his hair blown around?
Other mistake: Vic and Stu get into a shoot out inside the animal hospital with some thugs, guns firing all over the place. The building is full of animals like dogs and cats and parrots. However, the animals stay completely calm and quiet during the entire gun fight and seem unaffected by the rapid, very loud banging of gun fire. Even right after it, a cat that just had it's tail stepped on sits on a dead body and meows like nothing happened. This is completely uncharacteristic of how animals would act to loud gunfire in an enclosed building, especially in a vet's. (00:45:00)
Other mistake: Jack's parents were at a Halloween party when his mother went into labor. Later in the movie when he's asked by his teacher he says his birthday is September 12th.
Suggested correction: The movie doesn't specifically say this is a Halloween party. This may simply be a costume party which can and do happen multiple times a year.
As you stated, it doesn't say it's a Halloween party. In fact, there's signs in the room that say "Beaux-Arts Ball."
Other mistake: Whenever Fozzie is driving the Studebaker, the movements of the car don't correspond to the way he moves the steering wheel (he tends to crank it back and forth a lot).
Other mistake: During the pub fight scene, the guy who got hit with the glass cup (Wound on his forehead), pulls a six shooter out of his pants, but he fires eight bullets at Harry's umbrella.
Other mistake: In Tiffany's converted garage, Tiffany says she's thinking of putting in a ballet bar, but there's one there already right next to the big mirror, where it's supposed to be.
Other mistake: When Gregory has read the note from Fregly, he realises he put his thumb on a booger. When we see Greg on the floor, the note should be nearby. Instead it is several feet from him, in line with the bin. This is strange as Greg only dropped it and the note didn't flutter over there as Greg only turned when he hit the floor. In fact, the movement should've moved it closer to him. In line with the bin is even weirder.
Other mistake: Duke is running through the city while dragging Max by his leash. A close-up shows Max being pulled between the bars of a metal fence, but the gap is much too small for Duke to have passed through.
Other mistake: In the race scene between Milner and Falfa, you can see exhaust smoke coming from Milner's car, but in a previous scene the station attendant mentioned Milner taking the header plugs off. By taking the header plugs off, his exhaust is running from the headers and you wouldn't see exhaust coming from the tail pipes. (01:03:15)
Other mistake: When Jim Carrey runs out of gas, and takes his what appears to be either a one or two gallon gas can and fills it, the quantity dispensed shows 5.74 gallons.
Other mistake: In the 'sped' class the teacher starts taking attendance. He goes through and finishes but he never calls the main girl's name or her friend.
Other mistake: When the NASCAR pit crew starts working on Herbie at the barn, they initially pull a bunch of parts and tools from their racetrack trailer. One man is carrying a distinctive VW-only wheel rim, which would definitely not fit their regular NASCAR car. The decision to race Herbie had just been made, so they would not have been carrying VW spare parts yet. Nor could they have pulled one of Herbie's wheels yet since they were still carrying the jack to the barn.
Other mistake: In the championship game, the Yankees batter hits a foul ball when they score their winning runs.
Other mistake: In the scene where Rosalee and Tad are talking on the airplane, in the background with the two airplane windows one is white like it's a cloud and the other one is blue like blue sky, and they don't change for the whole talking scene. So it's like they stopped in mid air.
Other mistake: The Russian flag in the Russian commander's office is upside down.
Other mistake: The little girl elf pours Santa a mug of hot chocolate, but if you watch closely there is nothing in the mug when he drinks it.
Other mistake: For the entire length of the movie, Bam Magera is referred to as Bam. But in the credits, his character's listed as Chad.
Other mistake: Just before the evil robots capture Bill and Ted's girlfriends, after they crash through the window, the girlfriends ask the robots: "Who are you?" and Bill goes "Well, I'm really Evil Ted!" and unzips himself and out pops Evil Ted, and the other robot goes, "And I'm really Evil Bill!" and out pops Evil Bill. When the robots are herding the girlfriends out just before knocking them out with their breath, you can see two sets of clothes in the bottom left corner if you watch closely.
Other mistake: When William Shatner demonstrates how to jump on the hood of a car, and slides off, he makes a big dent, but when the camera angle switches, the dent's no longer there.