Does this happen every time? Where in the route does this happen?
It'd actually be quite interesting to see the static AI train derail..
I've witnessed the AI train derail many times on the Q.
I don't know if it had a speed limit, but it seems that the AI would always love to pick up speed on the Manhattan Bridge before entering the tunnel to DeKalb Avenue, thus derailing at the curve where the N and Q would diverge.
I was playing on an older version of the route, so I don't know if it still happens with the current Q route.