The same actor was Kevin McCarthy who in the original jumps on the back of a truck and to his horror sees it full of the alien "pods" which are taking over humans. Directed by Don Siegel from the novel by Jack Finney.

That was to be the original ending but the authorities got the wind up because it would have caused moral panic, so the film maker had to top and tail the film with a couple of bromide scenes where McCarthy is telling his story to a sceptical police chief, and then we flashback to how it all began. Then they tacked on a scene at the end where info comes in that persuades the police McCarthy is telling the truth. So ruining what would have been a stupendous finale. I bet Don Siegel was grinding his gnashers to bloody stumps.