Factual error: The movie takes place during the 1990s, but throughout the movie cars are shown with Illinois license plates with "Illinois" written in cursive. These plates were not introduced until 2001. (00:24:45)
Factual error: At the start in 1989, when Mike is dancing with the cheerleaders and also just before he goes after Scarlet, in close-ups of the crowd cheering there is a man (with a white baseball cap) wearing a Paramore t-shirt. However, Paramore (a Grammy-nominated American pop rock band) formed in 2004. The style of t-shirt he is wearing is actually one of the officially licensed Paramore merchandise. (00:02:45)
Factual error: In the scene where Tucker is talking with Hugh Hefner, the chess board in the background is set up backwards. The pieces are basic Stanton style, and the kings and queens are obviously in the wrong positions.
Factual error: Two of the albums sent to Larry by the Columbia Record Club are Santana's "Abraxas" and Creedence Clearwater Revival's "Cosmos Factory". The film takes place in 1967. Both albums were released in 1970.
Factual error: After James leaves the bar and is driving, you see a dealership in the background and you can see new trucks and a new model yellow mustang. The movie takes place in 1987, so the vehicles are about 20 years too new. (01:26:00)
Factual error: If you're a Hertz #1 Club Gold Member like Ryan is, you don't need to swipe your card or sign for a rental as shown in 2 scenes. You just go to your assigned car in the lot and show your driver's license at the exit.
Factual error: When Larry and Amelia's plane takes off, the cables it is held onto easily rip off from the canvas. For security measures, a real cable would be made of steel, therefore ripping the structure instead of just snapping like a string.
Factual error: When the guys first set up the website to accept submissions, the year is 1997. We see a shot of the computer screen which displays that they are running Windows XP, which wasn't released until 2001.
Factual error: After trying to get his balloon back, Carl Jr. falls and breaks his arm. The ambulance that picks him up has a modern-day electronic siren, when in the 30's it would be a mechanical siren and would be much smaller.
Factual error: When the TV news vehicles are leaving the hospital, supposedly set in Oklahoma, the ocean is briefly visible in the background.
Factual error: Many of the songs featured in the film, almost all of which are portrayed as being singles actually being played by the disc jockeys, came out after the 1966 setting of the film, including Procol Harum's "A Whiter Shade of Pale" (June 1967), Tommy James and the Shondells' "Crimson and Clover" (November 1968), The Who's "I Can See For Miles" (October 1967), Jimi Hendrix's "The Wind Cried Mary" (May 1967), the Turtles' "Elenore" (November 1968) and Herb Alpert's "This Guy's in Love with You" (April 1968) among several others.
Factual error: During the stop in the small town while still in Texas, and Tallahassee breaks all the windows in the minivan, a Bank of Coweta sign is visible over one of the buildings. The Bank of Coweta is a local bank in Georgia, and has no branches outside of the state.
Factual error: In the movie they search for two matching rings, which contain geographical location of the treasure. The rings were casted in 1589, and uses Greenwich as Prime Meridian. This wasn't established however until nearly 300 years later in 1851.
Factual error: In the credits, Josh Peck is said to voice Rudy. He actually voiced Eddie.
Factual error: When they arrive at the airport to go to Hollywood, they show them arriving at Birmingham Airport where they are to start their 11 hour flight. However, Birmingham Airport doesn't do flights to LAX.
Factual error: After the chase scene through the desert and arriving at the abandoned old house, the children hand the taxi driver all of the money they received from the ATM earlier in the movie. When the taxi driver examines the money, it is all hundred dollar bills. No ATM in Las Vegas, Nevada dispenses hundred dollar bills.
Factual error: When the super-scrambled monster is destroying the town, everything it destroys falls down completely, despite the fact the monster only hits one side of it. (01:00:15 - 01:04:40)
Factual error: Paul has hypoglycemia. When he eats the lollipop off the floor and gets up instantly, this would never happen as it takes the sugar a while to get into the bloodstream. He would never be instantly cured.
Factual error: In the scene of the parking garage in Vegas, as the group is escaping the Trekkies, you can see vehicles in the parkade from the 2000's. The movie is taking place in 1998.
Factual error: Herzog is referred to as "Oberst" (Colonel) both by The Wanderer and in the end credits. But both he and his men wear SS uniforms and insignia, where standard military titles were not used. Herzog should have been called the SS equivalent "Standartenführer".