After I put the handle on the pull string, it still told me the pull string was missing a handle when I clicked on it. It worked once I got everything else in place, but it was a confusing error that made me waste time looking for something else to add to the handle.
I really like this game, but I have one petty complaint. The badge for killing 5k enemies is pointless. I had the game beaten after killing about 2k enemies, and didn't even go to the last level until I had the best ship and the minigun. When each level has less than 100 enemies to kill, that means way too much replaying to be fun. Other than that, fun and easy game.