When Peter starts building in Tony Stark's secret lab for the first time, Happy puts on AC/DC song "Back in Black." This is the same song that was playing in the first Iron Man film, when Tony was ambushed and kidnapped by the 10 Rings. AC/DC's "Shoot to Thrill" was featured in both Iron Man 2 and The Avengers during scenes with Tony Stark. Clearly, he has a thing for them.