When I exit a minecart, there is a significant chance that I will glitch into the floor (or right through it if it's only 1 block thick). Though it doesn't happen most times, it happens often enough to be absolutely infuriating. Though it mainly happens in rooms or tunnels that are only 2 blocks tall, it can also happen with a higher ceiling. It can happen when there is a wall on only 1 side of the minecart, as shown in the screenshot. I don't know if the direction matters, but in this screenshot, the wall is to the south of the minecart. I've also had this glitch happen when the wall was to the east.
This glitch is much more likely to happen after I ride the minecart a significant distance than if I just get in and out repeatedly without moving the minecart.