For me it was all pretty smooth going, (which is pretty unusual lol) but I did have one disaster mid development. My game revolves around racing against NPC players. the NPCs are just pre recorded ghost data, so any change to the course would get them out of sync. You can probably see where this is going, so I had just finalized 50 ghost data replays, and gave it to some testers, but they didn't like the movement controls and the level was WAY too hard. This meant I had to discard all the ghosts so that I could adjust the physics and course design without any weird playback. I managed to get all the ghosts re-recorded with the help of a friend, but it was a pretty bad mistake! Just another reason to playtest often!
here's the game: https://itch.io/jam/brackeys-14/rate/3850016