The game sometimes crashes when I'm placing trains - I think it has to do with the new snapping feature near train stops. But I can't reproduce it consistently. Not sure if it has something to do with the rail setup. I copied and pasted a test setup from my normal freeplay map (where I first noticed this bug) into a sandbox map and was able to make it crash once.
Steps to reproduce:
Place several train stops after each other.
Pick up a train from your inventory and rotate it correctly.
Whirl your mouse cursor around until it crashes. It doesn't always crash immediately.