Russell Brand may not get a line (he's probably too busy sparking a revolution anyway), but Dr Nefario makes a small, background appearance during Villain-Con. After all, being considerably older than Gru, he was likely active back in the sixties, so of course he'd turn up at the biggest collection of villains in the world. Nefario is seen showing off the freeze ray, one of Gru's signature weapons from the Despicable Me films (and no doubt one that went down better than the Fart Gun). As that weapon is what Gru uses when he introduces himself near the end of the film, that probably means the two have already had some interaction by this point. Another prequel?
