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: 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: 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: Arnold holds a hot stick of metal to Marion's face in her bar, threatening her. In the opposite angle, the metal is nowhere to be seen when it should be right next to her face. Cut back to the other angle and we see it again.
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: The amount of dates change from shot to shot before they are poisoned.
Continuity mistake: At the market in Cairo just after one of the guys tries to kill Indy with a sword and misses, the shadow from the wall changes between shots.
Continuity mistake: When Indiana is fighting the bad guys at the market in Cairo, one of them kills another one with a sword instead of Indy - their position changes between shots.
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.
Continuity mistake: Belloq grabs the idol from below its ear. When the angle changes he is holding it by the idol's temple.
Continuity mistake: The huge rock rolls down to ground level, but when the angle changes it's back on a levelled position.
Continuity mistake: The position of the door through which Satipo escapes with the idol is inconsistent in every shot, sometimes it's higher, then almost closed, then back to open.
Continuity mistake: As Marion initiates the drinking challenge with Belloq, from the front she quickly tosses the drink back, tipping her head back then forward. From behind she repeats the motion.
Continuity mistake: When Indy is shot in the arm in the car, there's no blood on the windscreen at first, but in the very next shot there is.
Continuity mistake: When the guy at the start who betrayed Indy is shown stabbed by many spears, in the shot when Indy says "adios", he stays with him the entire shot. However, in the next shot, he's far away from him.
Continuity mistake: When seen from the outside the entry hole to the Map Room is quite vertical. The angle is different when seen from the inside. Further, the hole is so vertical that the sun wouldn't be high enough to shin through the hole at 9 am.
Continuity mistake: The amount of moss behind the idol increases between shots.
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.