In The Timecop Movie, How Did They Get Back Into The Rocket Sled Thing For The Return Trip

They go out inside a rocket sled but get dumped into the past sans any sort of vehicle, and on the return trip they walk through an FX ripple but somehow wind up back in the rocket sled to go back to HQ.  How the fuck does that work?  Where is the rocket sled while they are in the past?  Is it open or closed?  These might be the most important questions in the last 150 years, but we have no answers.  Thanks, Trump.