Other mistake: After the magnet grabs Slink during the incinerator scene, all the toys grab metal objects to avoid getting torn up. Afterward, they all let go of their metal objects to drop down. However, Slink also drops down despite not holding on to anything because he is made of metal.
Suggested correction: Or, the other toys helped him down.
Other mistake: When the ride finishes, there is no sign of a safety bar in Gru's cart.
Other mistake: Flynn and Rapunzel go through the Snugly Duckling tunnel. Later when Maximus points to it, you could easily see it from anywhere in the pub. But nobody saw Flynn and Rapunzel go through other than the thug who showed them.
Other mistake: As the movie opens, Yogi is using a telescope to watch a family at a picnic table. The reflection in the lens should be in reverse but it is not. It shows the same view.