Apart from what was mentioned, there is a problem with background graphics when playing full screen. It's shifted to the right.
The score is displayed on top of enemies, which is a bit inconvenient. You can fix these issues easily.
The controls could also be improved. IMO WASD and mouse click or arrows and space would be a bit more convenient.
But overall, I like the gameplay, the graphics and sound FX with the soundtrack. Well done guys!