Visible crew/equipment: When Indiana frees Marion, locked in the cabin pilot of the Nazi plane just after one of the soldiers is killed by the blades, a set light is reflected on the plane's glass. (01:20:32)
Continuity mistake: When the Nazi soldier is killed by the airplane blades, some of his blood splatters on the pilot cabin glass where Marion is, but in the next shot, the blood has totally disappeared from it. (01:20:24)
Suggested correction: This is incorrect. First, the blood splatters on the gunner's turret cabin glass, not the pilot cabin one. Second, Marion crawls from the gunner's turret cabin to the pilot cabin, where there is no blood. Also, this last point is not shown exactly in the next shot, as this mistake suggests.
Continuity mistake: While the Ark is killing the soldiers, the cameraman is hit twice, as the first hit is shown in the first wide shot of the dying soldiers and the second when the camera focuses on the cameraman. Also, during the second hit, a beam passes through the camera and strikes the cameraman in the face, although he remains standing. In the next shot, the cameraman's body is suddenly on the ground and the beam that had killed him disappears.
Continuity mistake: As the truck pulls up next to the Command Tent, four soldiers lift the Ark's box and a fifth soldier, positioned between the two wooden posts of the Ark's box and to Gobler's right, picks up the sticks that Indy and Sallah had used. In the next shot, that soldier is now to the left of Gobler and the Ark's box. (01:21:40)
Continuity mistake: On the Bantu Wind, after Dietrich takes Marion from Katanga and begins to leave, the soldier next to the pipe where Indy hides throws his cigarette and leaves the scene. In the next shot, when Belloq stops Dietrich, the soldier is now back at his original position. (01:36:51)
Continuity mistake: After Toht's command, the Mongolian and the Nepalese grab Marion, then the former puts his hand on Marion's cheek. During this, the Nepalese faces Marion, whose mouth is open. In the next shot, the Nepalese is suddenly looking at Toht, Marion's mouth is suddenly closed, and the position of the Mongolian's head has changed. (00:30:28)
Revealing mistake: While Indy and Marion are in the Well of Souls, and they encounter the snakes, Indy falls to the ground only to be confronted by a hissing Cobra rearing its head. Look carefully and you'll see the snake's reflection on the safety glass between it and Indy. Briefly you can also see the torch's reflection while he's waving it around. You can also see Marion's reflection when she falls in later on and is face to face with the cobra. [This has been corrected in the new DVD set. You can only see it if you have the original VHS. I think it's visible in the "making of" on the DVD as well.]
Continuity mistake: When Indy goes to save Marion in the tent he removes the handkerchief gag. But when he decides to leave her there, he puts the gag back on and some of her hair gets caught underneath the gag on one close up shot from the left. But when the camera goes to the back of Indy, her hair is no longer caught underneath the gag. (00:56:00)
Continuity mistake: Near the beginning of the movie where Indiana is running away from the tribe of South American Indians after Belloq robs Indiana of the gold statue, in one shot you can see that the Indians are only a few meters behind Indiana, but in the next shot, they are at least 50 meters behind. (00:11:20)
Revealing mistake: Watch the shadow of the stone Indy pushes out to escape from the Well Of Souls - it bounces down the sand dune, exactly the way a large rock shouldn't. (01:15:30)
Plot hole: When Indy and Sallah visit the gentleman who translates the staff headpiece for them we hear the staff should be "six cadams high." Indy replies, "About 72 inches." Then, turning the headpiece over, "Wait - take back one cadam to honor the Hebrew God whose ark this is." It's definitely referring to the staff length - Indy says afterwards "Their staff is too long." So, about five feet now, right? But, when Indy goes to the map room the staff is much taller than him. If the staff is about five feet high, Indy would be around three feet tall. (00:48:25 - 00:53:05)
Visible crew/equipment: As soon as Marion gets locked in the cockpit of the Nazi plane, you can see a crew, a blue van, a ladder, and a crew member with a white sleeveless shirt and a big brimmed hat, all in the reflection of the glass. (01:18:20)
Continuity mistake: Before the shoot-out in Marion's bar, before the Nazis enter and ask her for the amulet, she's sitting alone at the table. She pulls the amulet out of her shirt, the chain still around her neck, and stares at it in the candlelight. The next moment the chain is not around her neck and she hangs the necklace onto the table centrepiece. (00:28:20)
Revealing mistake: After Indy gets behind the wheel of the truck containing the ark, he jerks the steering wheel to the right to run the pursuing jeep off the road. He then jerks the wheel to the left to hit an upcoming motorcycle. In neither case do you see his body sway with the presumably drastic swerve of the truck. Apparently this was filmed in a stationary vehicle, or one in tow that was fitted with a prop steering wheel.
Revealing mistake: When Indy fights the driver of the Nazi truck, he gets thrown through the windshield, and eventually ends up underneath the truck. When he is climbing underneath the truck, heading towards the back of it, you can see the trench that was dug down the middle of the road to provide the stuntman (this being one of the few stunts that Ford didn't do himself) with the extra room needed to do this feat. (This is backed up by DVD commentary. The director stated that the truck was too low to the ground so they had to dig the trench in order for there to be enough room for the stuntman). (01:27:50)
Factual error: The film starts in the year 1936, and just like the RPG Indy uses to threaten Belloq with, the MP40s (or at the earliest, MP38s) are an arms-historical anachronism in this movie. As the numbers in their names imply, the MP38 was first produced in 1938. The weapons in the movie are not the similar-looking ERMA MP-36, you can see the ribbed, vertically angled magazine holders typical for the MP40 - its predecessors had either a 30°-canted, smooth magazine holder (MP36) or a round viewing port for checking the ammo (MP38). (01:31:45)
Continuity mistake: When Indy is distracted by the young girl and her eyelid message, the girl changes from a window seat to another row when the bell rings to end class.
Continuity mistake: In the Himalayan bar scene when the sherpas leave, Marion starts to pick up the shot glasses and puts them on a tray - there's a large group left at one end of the table, one in the middle, and two by a bowl at the other end. When she returns for the rest, the two by the bowl have vanished. (00:26:20)
Factual error: The captain of the Bantu Wind, Katanga, wears a hat that originated from the Yugoslav People's Navy. But the Yugoslav Navy wasn't formed until 1945, 9 years after this movie takes place.
Factual error: During the fight scene at the German flying wing, the pilot ducks into the plane and pulls out a pistol and cocks it. The pistol is a P38 9mm semi-auto that the Germans did not issue until 1938, two years later.