Super fun game! I love the music and it's super cool to watch them put out the fire once you beat a level, especially in later levels.
Also, I'm not sure if this is intended or not, but I noticed that the firemen succeed in passing the bucket regardless of which arrow key you press. I was expecting that you had to press a different arrow based on where they were pointing.
I would also suggest that instead of restarting the whole level on a missed beat, it would go back by 1 fireman. It can be frustrating having to restart an entire level later on when the levels get longer.
Regardless, I had a lot of fun playing this! Great work!