possibly related to MCPE-7829, but yesterday we encountered a different issue:

We've been playing multiplayer, Local WLAN. The host was ~10000 blocks away from spawn exploring the world. I was traveling our railway from the jungle to our spawn location. (Lots of curves and all).

Suddenly, The Host teleported into a minecart in front of me, we both collided and swapped directions.

Plus: We had one (and after some more travelling, several) minecarts more than we had previously

Contra: It was quite hard to get to the spawn island, as we changed direction and teleported on the track several times.

Contra: Teleporting occured to both client and server from time to time, regardless of whether he/she was inside a minecart or not, when one of us travelled in a minecart.