Goofs

Poppy's braces disappear during the tree house scene.

When Gru is taking the girls to school for the first time after moving house, the Minions attach the baby capsule to the center rear seat of the van. Then after they arrive at the school the baby seat appears on the rear right seat.

By the end of the movie, on the rooftop of the high-rise building in construction, a metal beam magically appears over the just collapsed hole in the floor.

One of the Alumni villain's wearing a luchador mask, is seen on the dance floor facing the doors when they first open, but is then standing facing the stage, off the dance floor, when the doors close.

When Poppy is flying away from Maxime's ship, the noise that Principal Übelschlecht's cart makes is that of a propeller aircraft, although the cart is powered by a jet engine.

The baby's car seat is facing forward. At his age he should be facing the rear of the car.

When Lucy inadvertently causes an electrical fire in the hair salon, the fire alarm is triggered first, and then the sprinklers are triggered. In reality, many sprinkler systems are designed so that when a sprinkler is set off, it triggers the fire alarm system in turn, not the other way around.

The vending machine that Ralph gets stuck in contains snack food and soft drinks, but soft drinks are never in snack food vending machines because they aren't refrigerated.

In the last scene at the prison, there are both male and female inmates. Men and women are always segregated in prison, to the extent that they are in totally different buildings.

In the 1st movie, Vector got stranded on the moon. And then, he got stranded on Mars in the short movie, Mooned. But in this movie, he was a prisoner at AVL Headquarters.

In the 3rd movie, Silas Ramsbottom retired from the AVL, and was replaced by Valerie Da Vinci. But in this movie, he came out of retirement to stop Maxime Le Mal. Because of this, it's unknown what happened to Valerie.

In the 3rd movie, Gru started to get along with Dru when he met him. But in this movie, Silas Ramsbottom said that his family can't find out about his whereabouts. When that happened, Gru was happy about it because he wasn't going to see Dru for a while. But since he was getting along with Dru in the 3rd movie, he should've been disappointed that he wasn't going to see him.