Indie’s costume was inspired by the one Charlton Heston wore in the 1954 movie “Secret of the Incas”.
From wikipedia:
“Throughout Secret of the Incas, the main character, Harry Steele, can be seen wearing what would later become known as the “Indiana Jones” outfit: brown leather jacket, fedora, tan pants, an over-the-shoulder bag, and revolver.[15] The character also sometimes wears a light beard, unusual for films of its time, and there is a tomb scene involving a revelatory shaft of light similar to the “Map Room” sequence in Raiders.
Raiders’ costume designer Deborah Nadoolman Landis noted that the inspiration for Indiana’s costume was Charlton Heston’s Harry Steele in Secret of the Incas: “We did watch this film together as a crew several times, and I always thought it strange that the filmmakers did not credit it later as the inspiration for the series” and quipped that the film is “almost a shot for shot Raiders of the Lost Ark.”
#7 Shot comparison of “Secret of the Incas” and Indiana Jones. Spielberg and Lucas stole the idea from that Charlton Heston movie.
“Premakes” Raiders of the Lost Ark (1951)... A frame by frame breakdown
https://www.youtube.com/watch?v=eE9-FcJnQGA
