New-U Station
The New-U station takes the form of the Lunar Base orbiting Pandora whenever you respawn. This isn't quite an Easter Egg but it is very subtle and a neat detail.
Crimson Raider Armor
The Crimson Raider shoulder pads and helmet are strikingly similar to the Brotherhood of Steel Power Armor in the Fallout series.
Wise Fwom Your Gwave
When you die and are resurrected at the New-U Station, you will hear various quotes. One of these quotes is the infamous line from Altered Beast.