I wanted to try the new gates, started a game in sandbox-mode, build a 100 tiles long straight railline, set up a train with 5 locomotives and went full power until the end. Result is i get a popup saying "Ok, so we didn't do the train movement right, let us know when this happens" So here i am, letting you know

It also seems to corrupt saves from the same map, can't place anything after loading an older savegame
I reproduced it 2 times, just by starting a new sandbox, building the line and driving on it.