Factual error: When the Fat Controller arrives at Tidmouth Sheds, Tidmouth Sheds appears to be missing from the reflection.
Factual error: When Nick, Kurt, and Dale are in Rex's closet, Dale appears to be turning on the gas. What he is turning is actually the screw to secure the regulator onto the gas cylinder. You can see the valve to release the gas at the top end of the cylinder. (00:46:30)
Factual error: In the opening heist, the gang of thieves wants to steal "The Medal of Zeus." A plate at the museum explains that in Ancient Greece, Olympic champions were awarded olive wreaths, up to the 88th Olympics in 424 BC, when a golden medal was given to the victor for the first time. This last bit about gold medals is just made up by the movie. But it also gets the timeline wrong; the 88th Olympics were in 428 BC. 424 BC is when the 89th games took place. (00:03:30)
Factual error: There are actually no dinosaur remains at the British Museum. There used to be, many many years back, but they were removed to the Natural History Museum, which is about 3 miles from the British Museum.
Factual error: Near the end of the helicopter scene Jenko pulls the pin of a grenade with his teeth before he throws it. It is not possible to pull a grenade pin with your teeth as it requires more force than that.