Continuity mistake: After the kliegs and generator explode, there is a shot of Belloq and Toht on the altar. Belloq has the ivory rod in a vertical position. In the next shot, the rod is horizontal.
Continuity mistake: When Indy and his excavation team arrive at the true location of the Well of Souls, we can see that it is on a low hill, just a few meters from the Nazi excavations. However, when it gets dark, we can see that the excavations have disappeared from view and now the Well of Souls appears to be on a considerably high mountain (taking as a reference the illuminated camp on the right of the screen).
Continuity mistake: Major Eaton's right hand moves from his ear to his mouth between shots. (00:17:34)
Continuity mistake: In the chapel, before Indy turns the chalkboard over to explain the staff of Ra and the medallion to the G-men, the chalkboard goes back and forth from tilting forward to tilting backward a few times.
Continuity mistake: When Toht frees Marion, Dietrich enters the tent, and a few seconds later, Gobler enters. In the next shot, Gobler enters first, with Dietrich second. (01:07:52)
Continuity mistake: When Belloq and the Germans are at the Well of the Souls, a top-down view shot when Indy yells, "Why don't you come on down here and I'll show you!" shows Belloq and a German officer kneeling down to the left of him, also looking down into the hole. But the side view shots show only Belloq standing near the opening.
Continuity mistake: When Indy is listening to the one Army agent he is in the process of putting his right hand into his pocket. In the next shot the hand is back on the leather case. (00:16:46)
Continuity mistake: When the Cairo Henchman pulls the knife on Marion, the blade edge changes position from down to up to down again.
Continuity mistake: During the truck chase, as Indy is fighting with the German driver, they knock over some scaffolding and a man drops down in front of the windshield. None of the workers on the scaffolding landed on the truck, much less the front of it. So, he shouldn't have been there.
Continuity mistake: In Indy's class at the beginning, the girl that lowers her eye lids to show the phrase "Love you", is looking in a totally different direction than the people behind her. They're all supposed to be looking at him, but the girls behind her are looking to their right while she is looking straight. They can't be daydreaming because they're all smiling and look infatuated. (00:13:58)
Continuity mistake: When Marcus enters the classroom he leans up against a wall and there are 2 girls in the front row next to him. When the bell rings, the girls are the first two students to leave the classroom. Seconds later when Indy looks over to Marcus the same two girls are just getting up from their desks.
Continuity mistake: Indy and a Nazi soldier are fighting in the cab of the truck when they come to a place where a stone building is being built. As the truck is driving into the scaffolding, several rocks come down and hit the truck and remove the rack from the top. Moments later the rack is back in place. (02:50:00 - 03:01:00)
Continuity mistake: As the big German engages Indy in the fight, Marion is removing the chocks from one of the wheels. In the wide shot you don't see her at all, even climbing the plane to knock out of the pilot.
Continuity mistake: When Indiana is confronted by the Cairo swordsman, he already has his left shoulder pointing towards his opponent in the shot where the crowd scatters. But in the following shot, where the swordsman is first seen, Indiana has his right shoulder pointing forward and is just turning around to his left side. (00:40:14)
Continuity mistake: While escaping from the boulder, right before the spiderweb scene, Indy runs facing forward and makes a right turn. A shot later from a wide angle he is facing backwards.
Continuity mistake: When Indy is driving the truck, chasing Belloq and his Nazi cohorts, the last Nazi guarding the Ark of the Covenant climbs to the driver's side of the truck and kicks Indy away from the steering wheel. The first time he punches Indy in the arm, Indy's blood is on his fist. However, the second time he punches Indy in the same spot, there is no blood on his fist.
Continuity mistake: In the bar shootout, a man is shot in the head, and as Marion screams in shock she's holding onto the table. In the very next shot her hand is much lower.
Continuity mistake: When chasing Indy in the truck that he has driven into a fruit market, the Germans in their car are surrounded by fruit sellers. One gives a German soldier a melon, who promptly throws it to the ground on the left side of the car. When the car pulls away, the broken melon lies on the right side.
Continuity mistake: Indy swings on the vine, and his bag is on his hip. As he gets up on the plane, it disappears, but the strap is on his shoulder again in the cockpit.
Continuity mistake: While Indy is chased while running towards the plane, he is in an open field where Jack the pilot can perfectly see him, but when the angle changes Indy is suddenly next to a forest.
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.