This was also the first test of my simple physics objects, and it seems to have worked. As is shown in the screenshot, the crates can sit on the moving platform with almost no problem (curse that one pixel difference!). The player can punch the crates and send them flying a certain distance, on a path that follows projectile motion.
I added frames in between each punch in the animation, and already it looks alot better. However, now the input of the combo is screwed up, so I'll probably have to redo that code. Next I have to add the ability to pick up and throw things, such as the crate.