I spent a bit of time jumping around the last level trying to figure out a way to get a secret ending, but either because it was non-existent or because of my own incompetence, I couldn't find it. It was disappointing too. In the final box where the game ends, there are two of those things that can be destroyed by turrets on the ceiling, but it seemed impossible to bring anything through there because it was blocked by an anti teleportation field thing. I tried firing bullets down the hallway and then warping onto them to try and bend them down into the final room, but I gave up on that since there's a wall there anyway.