Heya, thanks for the feedback!
Yea, I've been having these problems with graphics in gamemaker a lot, I will look into that so that I can avoid these problems in future.
About ending - yes, you are right, it does indeed need some "proper explanation" that the game ended. I'm just really into oneshot-like games where game can just close/write something to text files on computer/and so on - so if I made this game for desktop it would just close in the end. But yea, I will try to avoid this kind of stuff while I'm doing web games.
And thanks for looking into that bug! Would really love to know what caused it.