The castle the school is based in has echoes of Schloss Neuschwanstein in Bavaria, south Germany, which was used as a location for filming of Chitty Chitty Bang Bang (1968). That this is deliberate is borne out by Gru, Poppy et al making their escape from the cast in a flying vintage car. Principal Übelschlecht's hairdo echoes that of Gary Oldman as the eponymous character in some scenes in Francis Ford Coppola's 1992 Bram Stoker's Dracula. When Gru and the three Minions enter the castle in the opening segments, the Minions don goggles that, with their suits, reference Men in Black.
In the award ceremony scene, there is a Martian from Mars Attacks in the background and when the roach plane breaks through the concrete, the pest control truck from MIB gets knocked over.
you didnt saw two references from the secret life of pets in despicable 4. 1 is when gru is packing his bag,he also put busy bee in his bag. 2 when maxime le mal is parking giant cockroach robot to put fuel in it we see a dog barking at his robot cockroach. that barking is looking familar than none other Max