There is a scene where Lance and Hunk are sneaking past the instructor's lounge at the Galaxy Garrison barracks. There is a man sitting inside the lounge eating dinner who looks like Roy Fokker from the Robotech/Macross anime series.
The trash cans that Lance and Hunk hide in are the same colors of the Lions they pilot later on.
After Lance, Hunk and Pidge fail their simulator test, their Commander dresses them down in front of other cadets outside the simulator. In the crowd of the other cadets can clearly be seen, front/right Miriya Sterling (from Robotech) and what appears to be Rick Hunter next to her. As Lance, Hunk and Pidge leave the simulator area and new cadets enter the simulator, you see two of them are Miriya and Rick again. Looking down on all of this from a window above is Roy Fokker, also of Robotech fame.