The premise of the episode is certainly an intriguing one: Montana National Guard three-man tank crew becomes isolated in the Little Big Horn area during June 25, 1964, and encounters events convincing them they are moving back to June 25, 1876, the day of the famous battle.
Creates a good sense of mystery and a feeling of being pursued and overcome by powerful unnatural forces -- and that's not easy to do. (Sudden, freakish wind gusts coupled with lighting changes create strong psychological shifts among two characters.)
But - and this is a big "but" - the tank commander, actor Ron Foster, has a working knowledge of the battle down to the most minute detail, which demands a greater suspension of disbelief by the viewer than the characters being caught in an historical time warp. This is exacerbated by the ponderous and dispassionate way he dispenses his knowledge to his crew, and we the audience.
I have published articles on the battle, and I would be hard-pressed to reel off the kind of knowledge Foster dispenses with almost nonchalant ease. (Another issue: A couple of "historical" references seemed to be the invention of writer Rod Serling.) I know Serling must have been suffering writer's fatigue at this point in the series' run.
I can only imagine what he might have done with this fascinating idea had he scripted it during The Twilight Zone's first year. It could have been one of his 10 best.
As it stands, it is a "what might have been" episode that misses. Still, it's fun to watch.
*WATCH the credits at the end superimposed over the M3 tank so prominently featured in the episode. Look carefully: There are images of Prell shampoo and Crest toothpaste in the treads. (Proctor & Gamble must have been sponsors, and here we are some 50 years later and they're still getting advertised.)