I'm not sure what to think of this one, and it only occurs when using a controller. You can see in this video that the first 3 times I shoot I am using the keyboard, the times where the bullet is weird, it's with a wireless 360 controller. Both events are identical as they both simply call the shoot function.
You can see at about 5 seconds I slow the video down and you can see what it's doing. It happens again towards the end of the video.
Now I've been working on this game for a few days, constantly checking it with a 360 controller and never saw this before. It happens in both node webkit and chrome.
Might just be how it is, but I wanted to check.