In Moonlit Sentinel 2, specific edges of the map (mainly at the south-west and the south-east) are tagged as Insta-Kill instead of being a proper death pit.
In Rainbow Sky 3, there are some issues with waypoints at the finish line if approaching it on off-road from the right.
Babel Drive 2 has some rings in an area that are placed under the level.
Spring Stadium 2 has a bad respawn point that results in immediately failing the loop and exploding.
Spring Stadium 2 also has some bottomless pits that are not tagged correctly.
Using "Restart" when watching a replay on some courses such as Spring Stadium 2 and Infected Shrine 2 may result in a replay desync. (This does not happen if one does "Stop Playback" -> "Watch Replay")
EDIT: There are some bad respawn points on Opening Act (results in a "crush" death), Dreamy Treeway 1 (results in respawning over a death pit) and Dark Fortress 2 (results in respawning over a trick panel).