Is there any graphical differences between weapons? because I change them but I always see the yellow line.

Good idea but needs more challenge! good luck!

I like "endless arcade with upgrades" games because they get harder and harder as you play and resource management also takes a big part on the gameplay experience.
However, one wave is always as hard as the other. I've fully upgraded two weapons and saw no difference between them.
Besides, if you're useng right click on Unity Webplayer you're suposed to toggle the "Hide Context menu" mode on build settings -> Player settings.
It's a nice idea, but needs to be worked on!