From the rules: https://ldjam.com/events/ludum-dare/rules "Certain Bug Fixes are allowed. You can’t add new features, but if something broke or didn’t work correctly as you were finishing up, you can fix this after the deadline. You are asked to highlight the changes you make in your submission (a short change log). You probably wont get a 2nd chance with some players, but at least it wont be a problem for future players."

(This seems like something that some people know and newer participants don't, so I wanted to highlight it here!)