I noticed that some of the gaps on the Bando map are really hard to impossible to fly through. Perhaps the colliders on trees are too big and hit the quad way earlier that the visual models. 

Here's a vid: 

Sorry for the sketchy flying, was on Snappy 2 and it was hard to be precise. Also one or two crashes were my own fault

Thanks for reporting, you're absolutely right - I use a faster but less accurate collision detection on some of the trees.

I think I will be able to fix that pretty easily for the next update by using accurate collisions on all the  trees on the custom levels.

Don't think it will be much of a performance hit either.

Edit: Issue has been fixed in the latest update (2017-12-10)