Although Anthony & Joe Russo are primarily known for directing Captain America: The Winter Soldier, Captain America: Civil War and now Avengers: Infinity War, time was when both of them were jobbing directors working on TV.
Among their credits is Arrested Development, a show that's so far removed from the Marvel Cinematic Universe that if it were a woman, you'd look at it and go, "...her?" Anyway, the Russos have littered their work with nods to their TV credentials in the past - Abed turned up in The Winter Soldier as a SHIELD technician - so it makes sense that they'd throw one in for Infinity War.
So, where is it? Well, if you'll recall the scene where Thanos is trying to find the Reality Stone (that's the red one) in the Collector's hideout - which, by the way, is also a mini Sicario reunion for Brolin as Thanos and del Toro as the Collector - there's a man in the background who's bright blue, wearing glasses and has a moustache.
Remind you of anyone? Not only that, the character is specifically named in the credits as "Character from Arrested Development" - but wasn't played by David Cross, as far as we know.