Most people like some Easter eggs in the films they watch, and there was plenty in the Avengers sequel, Avengers: Age of Ultron, but director Joss Whedon was for the most part way too tired to focus on the film as he’s said before in an interview:
“Yeah, there aren’t a ton of Easter eggs. It’s so hard for me to make a movie, especially this movie, I don’t spend a lot of time going, “You know what else would be hilarious?!” I’m more like, “Was the gun in the frame? Oh my God, I’m so tired.” I mean I would leave set every day and go home and write because it wasn’t quite right; it wasn’t quite finished. It needed to be better. So not a ton.”
Not a ton but some, and this is where ScreenCrush picked up on a Buffy The Vampire Slayer easter egg in Thor’s vision of Asgard. In one of the scenes three masked men in a doorway were wearing a wolf, Ram, And a Stag mask. This was a nod to the Buffy Spinoff, Angel, were these were the villainous trio.