Factual error: Aquaman lifts a submerged submarine towards the surface, which should start to sink again straight after releasing it, as its ballast tanks are still full of water. It shouldn't stay floating like that.
Factual error: While bidding on eBay for the steering wheel, Vanelope tries to up the $350 bid by bidding $1,000. This scares off the real bidder, but Ralph and Vanelope don't understand how eBay works and bid against each other until they win with a $27,001 bid. That's not how eBay works. Vanelope's initial $1,000 bid wouldn't have set the high mark, but would simply have been her maximum bid in case the other bidder kept increasing his bid. The current high bid would have increased by the increment amount until it reached Vanelope's max bid. Now, it could be that the system recognized Ralph and Vanelope as separate bidders and that's why it let them keep upping the max bid. But, if the system had responded normally and simply increased Vanelope's bid to $355 with a max of $1,000, they might have realised what was going on and not started bidding randomly.
Factual error: Peter sneaks off the bus using the emergency exit window, which would have triggered an alarm when he released the red safety latch, ruining his stealthy escape.
Factual error: When Mary and the children go to the bank the long shot of the bank shows a statue that was not erected until 1994.
Factual error: The police officer that shows up does two stupid things in a row that real police would never do. When investigating a kidnapping, he calls in what the car was they were looking for. Which he sees. Instead of calling for back up, or even mentioning to dispatch that he found a car that looks like it, after coming from a murder scene at a gas station and following a map left behind to this spot, he approaches the car alone, without calling for back up, or drawing his weapon. Shortly thereafter, he finds the kidnapped boy inside the car, who tells him the man who took him is in the house. The officer then proceeds to go into the house alone to look for a dangerous kidnapper without waiting for backup, even mentioning to the kid that his partner is on the way. (00:32:00 - 00:33:35)