I just discovered this after playing the new snapshot; I was riding a Strider around the nether, and after getting on, I can't get back on the strider. Something else I found was that thrown items were thrown as if I was still on the strider. This is true for arrows as well. It seems like the game still thinks I'm riding the strider.

Here is a video if you need more details.
https://www.youtube.com/watch?v=g4-1cB-4Cw8

Update: I found something else while experimenting a bit more after I made the video; shooting an arrow upwards and letting it hit the strider makes the player take damage. When the strider died to a ghast, it teleported me to where the strider was when it died.