As much of a train wreck as all that sounds it's actually more dull than anything else. The historical events are all short with background sets that look like they were just slapped together with stuff found laying around the studio, there's a bunch of mysterious stock footage (the burning train came from 1939's DODGE CITY) and the actors all look pretty embarrassed.
Worth a watch for the curiosity value, but I'd be much more interested in reading about how this misguided turd ever got green-lighted in the first place? Also what was the budget and did it make any money at all? What did audiences and critics back in 1957 think? I've done some searching but about all I can find is a write-up in the book "The Fifty Worst Films of All Time" where they quote Newsweek as saying "...some of the weirdest casting ever committed". A 44-year-old Hedy Lamarr as 19-year-old Joan of Arc or Harpo Marx as Sir Isaac Newton...yeah, I agree.
"The Great Clock of Outer Space"