As a kid when did you first see this? It came out in 1965.
Harrison Ford's first acting gig was a forgettable one-line in a movie that came out in 1966. He did American Graffitti in 1973, but it was another four years before he became a name actor in an obscure sci-fi/fantasy movie.
I'm so old, I actually saw this at the theatre when it was first released. After the third one in the series came out, our local theatre ran a "Man with No Name" marathon one weekend. The line-ups went around the block.