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)
Continuity mistake: When Indy runs over the sergeant, the background behind the truck changes between shots, going from the desert to a mountain. (01:28:45)
Revealing mistake: When the German staff car comes into the market place to find no truck, watch as Dietrich hurls the melon - the Gestapo guy in the front is obviously a dummy for this one shot. (01:29:40)
Revealing mistake: When we have the exterior shot of the ship that Harrison Ford, Karen Allen, and the Ark are aboard, specks of dirt can be seen over the view of the ship and the ocean - obviously, it was filmed through the window of another ship. (01:31:35)
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)
Factual error: Look to the right of the table lamp, there is a bottle of Myers Rum that has the modern plastic (silver/clear) cap and plastic pour spout. Not 1940s era. (01:33:10)
Continuity mistake: Indy looks at the Wurffler through the binoculars. In the next shot, when he takes them off and looks at Katanga, the submarine has moved to the left and astern. (01:34:58)
Continuity mistake: When Marion arrives on the deck of the Bantu Wind, Dietrich turns to look at her. Katanga is in the background, behind the colonel. But, just before Marion hits Dietrich, Katanga appears on the opposite side from where he was and catches Marion. (01:36:00)
Continuity mistake: In the Bantu Wind, the right arm of the soldier standing next to where Indy is hiding changes its position twice during Katanga's and Dietrich's speech. (01:36:18)
Continuity mistake: When the Nazis board the Bantu Wind, there are some shots of the pipe Indy is hiding in. During these shots, there's a big grey pipe right behind Indy's pipe. However, in the rest of the Bantu Wind shots, this grey pipe is on the left of Indy's pipe, not directly behind it. (01:36:19 - 01:37:05)
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: In Geheimhaven, Indy watches the submarine hidden behind some ropes. When Marion comes out of the submarine and the camera focuses on the back of Indy's head, the ropes disappear. (01:39:13)
Factual error: When Indiana Jones ambushes the Nazis with the Ark, he threatens them with an anti-tank rocket. This is set in 1936, and anti-tank rockets weren't developed until the American M1 in 1942. The Germans immediately copied it from captured weapons and made their own much larger version known as the Panzerschreck, then Panzerfaust. The Russian RPG which Indy is holding was developed from the Panzerfaust in 1949. (01:41:55)
Continuity mistake: Dietrich asks, "If we refuse?" Next to him stand four soldiers in a row, looking at Indy. In the next shot, the soldier who was holding a rifle is gone, and the two with machine guns are now giving their backs to Dietrich. (01:42:52)
Continuity mistake: When Belloq grabs the machine gun, his left hand is on the trigger and his right hand on the gun cartridge as he turns round with his back to the camera, but in the next shot, his right hand is on the trigger and his left hand on the cartridge but in the next shot, his hands have changed position once more, this time left hand on the trigger and right hand on the cartridge. (01:42:55)
Continuity mistake: In the canyon, in the shot of Toht, just before Belloq says "Do as you will", everyone in the background (Marion and her two guards, Dietrich, some soldiers) is gone (taking as reference the giant stone behind Belloq and the characters' positions in the previous and next shots). (01:43:49)
Continuity mistake: As the Ark is placed on the altar, Toht moves to the left of Belloq. Behind the German, a soldier without cap can be seen filming with a hand-held camera. In the next shot, that soldier has moved to the opposite side of the canyon and is squatting. (01:44:24)
Continuity mistake: Over Belloq's left shoulder and behind Toht, a soldier stands next to a klieg with a machine gun. In the next shot, the soldier's gun has disappeared. (01:44:25)
Continuity mistake: When the two soldiers place the Ark on the altar, they move to the walls of the canyon, and Toht stands next to Belloq. A few shots later, the soldiers are next to the Ark's poles (where they will be in the next shot), and Toht seems to be very huge. (01:44:39)
Answer: The scene you describe was indeed filmed. It was cut out of the US release of the film although I cannot speak for the Australian version. The scene also appears in the Marvel Comics adaptation. http://www.theraider.net/films/raiders/deleted_scenes.php has a list of this and the other deleted scenes.
Phil C.