Peter Quill: You're like Mary Poppins.
Yondu: Was he cool?
Peter Quill: [Pause.] Yeah, he was cool.
Yondu: I'm Mary Poppins, y'all!
In the beginning of the movie when the guardians are getting ready to fight off an inter-dimensional being Rocket winks a couple of times at Starlord. Starlord then responds but is looking to his left at Rocket, whilst Rocket is on his right side. The scene is for no reason mirrored, proven by the big orange device behind him also switching from being on his left to on his right.
David Bowie was meant to have a cameo, but tragically passed away before his intended scene could be filmed.