The Dress
The film was inspired by the super low-budget, fast-paced, predictable serials which preceded theatrical films in the 1930’s and 1940’s. One of the more predictable stereotypes of these episodic short films that connected to tell a longer story was the damsel who must be saved by the hero. These women were almost always dressed in ways inappropriate to the action in which they found themselves. Marion is clearly not directly inspired by these characters and the dress given to her by Belloq becomes a symbol of the independence and lack of damsel-ness inherent in her character.
Snakes
Snakes serve a dual purpose as symbol. Firstly, they become the reference point of Indy’s humanity. Unlike James Bond or Tarzan, this is an action hero who is shown to have an actual fear. That being said, snakes are also the symbol of his tenacity and determination; despite his fear of snakes, he won’t allow himself to be paralyzed into inaction even when climbing into what is essentially a giant pit of vipers.
The Ark
Simple: the climax of the film makes it clear in no uncertain terms that God exists and, what’s more, that He is way too powerful to understand or control.
Indy's Fedora
The hat which seems almost always affixed to Indy’s hat when he’s not in the classroom is as much a trademark of his iconic appearance as his whip and jacket. Unlike the whip and jacket, however, the fedora seems to be amazingly resilient when it comes to dealing with all the action and adventure and precarious escapes from imminent death it must endure. Heck, it even survives the swim to the submarine. (Though how even Indy survives a trip aboard the exterior of a sub is a pickle of a mystery.) The hat is the symbol of Indy’s greatest gift: tenacity and determination.
The Warehouse
The warehouse is the true symbol of evil in the film. Even more so than the Nazis. The Germans, after all, can be defeated and disposed of. But how long will the Ark of the Covenant remain hidden away inside a vast government warehouse? For as long as it remained buried beneath the North African sands? The warehouse represents the hiding of knowledge, the protection of ignorance and the isolation of ideas deemed too dangerous for the many by a selected a few.
