Same thing happened in my Frosty Fjords region when trying to connect my railway to the bridge. The game would crash when trying to connect road and rail, and at times it would go haywire as you described, a phantom railway would just randomly shoot out over the fjord towards the other bridge, and I would have to remove the track I laid which spawned the phantom track. I since worked it out on my own but it was frustrating, especially with the game crashing.
Even with a fully connected working railway across the bridge, the bridge still has buffers at one end implying the bridge is out of use, and trains just run through them. A small nitpick to be sure, but there are still kinks to smooth out. I also dislike trains running through each other on the same track, and setting dual tracks just means trains won't run properly as well as taking up even more valuable space. My biggest gripe is the emphasis the game has always had on expanding and growing the population, and yet we're expected to rip up our cities to lay down railways which add nothing to the population, and in fact we have to decrease the population to put stations and tracks in. I managed in two regions where I was just starting out, and had the room to put railways in.
