hi ceylanae! that bug honestly sounds pretty worrying, did the cars explode as soon as you started, or did you just find that you couldn't move the points they were on (the grey ones)?
If it's the latter, yes, you're not supposed to move or separate points when cars are moving through them, but can still combine grey (blocked) points with any other ones, that's actually the key to solving that level
if something else is going on, please let me know!
take care