The country that Dru lives in and Gru originates from is the fictional European country of Freedonia. This is the same name as a similar fictional European country in The Marx Brothers' movie Duck Soup (1933).
Near the start of the film as Gru and Lucy are racing to the ship in mini subs, they show two clown fish, with one looking bigger than the other. One of the subs then hits the smaller one and all we see that is left is that fish's fin. This is most like a reference to the "Finding Nemo" movies, as Nemo had a bad fin.
This is the first Illumination Entertainment film to be produced in a 2.39:1 widescreen aspect ratio; all of the company's previous films, plus the previous "Despicable Me" films, were produced in the taller 1.85:1 aspect ratio.
In one scene in Gru's lair the Minions are standing in front of a big computer machine with a green screen. The screen is actually displaying the Page R (the music sequencer screen) from a Fairlight CMI synthesiser series II which cost around £30,000 when originally launched back in 1982. It is unclear from the brief appearance in the movie what is being played back on the screen.
The song the Minions sing in the singing competition, "I Am the Very Model of a Modern Major-General", is from W.S. Gilbert and Arthur Sullivan's 1879 comic opera "The Pirates of Penzance". The competition is obviously a nod to the various singing reality shows like "American Idol" (2002) and "The X-Factor" (2011).
When Bratt stomps on the Hollywood sign, he leaves the first three letters alone, so it just says, "HOL". There was a game in the 1980s called "Human Occupied Landfill," and the cover of the book just said HOL.
This film features Balthazar Bratt as the new villain. Other villains in the "Despicable Me" franchise have been Vector, El Macho and Scarlet Overkill--voiced by Jason Segel, Benjamin Bratt and Sandra Bullock respectively.
The army of Bratt dolls that Balthazar Bratt sends to kill Gru are referred to as "the Bratt pack". This is a clear reference to the name given by the media, to a group of 1980s actors, popular for films such as The Breakfast Club (1985) and St. Elmo's Fire (1985).