Continuity mistake: After grabbing the idol, the cave starts to collapse, filling the place with rocks and rubble. When Indy starts to run, from the angle behind the floor is clean, rocks starting to fall for the first time.
Continuity mistake: Satipo drops the whip half a meter away from the closing gate, then runs away. However, when Indy rolls underneath the door, the whip is laying right next to it.
Continuity mistake: In the submarine dock of Geheimhaven, Captain Mohler is a man with dark hair in his mid or late thirties. But during the procession, he seems to be much older, with grey hair.
Continuity mistake: When Indy stands inside the Map Room, looking at the model of the city, the rays of the sun are to his left, and they move right and down as the sun rises. But since the entry hole is behind him, that would mean that the sun would be to the right when standing outside - but it was to his left when he entered the hole.
Continuity mistake: There is a shot during the truck chase scene where a Nazi falls out from the back of the truck and goes through the windshield of the car behind it. During the shot from inside the truck, we see two Nazis to the left. The one closer to the camera pushes the other one down. However, in the very next shot, we see that pushed-down Nazi immediately sitting up straight.
Continuity mistake: When the temple collapses, Indy is holding the idol with his right hand against his chest, and the left hand free and arm extended. A frame later, both arms are extended and holding the idol.
Continuity mistake: While Indy is in the Well of Souls, Belloq greets him and is standing by one of the four sides of the rectangular hole. A frame later he stands by one of the corners.
Continuity mistake: From the outside, the sides of the hole to access the map room are in shadows, from the angle inside they are sunny.
Continuity mistake: During the truck chase scene, the radiator bars Indy hangs onto keep swapping back and forth from bent outwards to slightly bent with no continuity at all.
Continuity mistake: When Indy is in the map room, he clears off the slot where the staff is supposed to go, right in front of a jagged line. However, in the split-second shot of the staff being inserted, it's not in the same hole. It's a bit to the left.
Continuity mistake: As the Nazis are preparing to leave Tanis, a soldier fires a shot into the air, causing several Arabs to fall to the ground and land in the middle of a circle of soldiers. In the next shot, as Belloq heads for the car, all the downed Arabs, the sergeant and the circle of soldiers have disappeared, with only the soldiers who were loading the Ark onto the truck remaining. (01:26:55)
Continuity mistake: Between the shots of Indy dressing as a Nazi and Captain Mohler reporting to Belloq and Dietrich, the Wurrfler appears to have advanced several inches forward (taking as reference the background behind the submarine, Mohler's location, and the fact that Belloq turns his head to the left to look at the Captain).
Continuity mistake: As Dietrich, Toht, Belloq and Marion board the Wurrfler, a naval officer descends the ladder and turns, his back to the ladder. In the next shot, he is facing the ladder.
Continuity mistake: The Angel of Death, judging from the position of the lid of the Ark (the two angels can be seen below the ghost), is located just above Dietrich's head. However, Toht screams as if it were right in front of him and Dietrich as if it were in front of Belloq (judging by their looks).
Continuity mistake: In the shot after Belloq's death, the generator and the rock Indy and Marion are on disappear.
Continuity mistake: Eaton and Musgrove are sitting, waiting for Indy to open the book. When Indy opens it, suddenly Musgrove is standing. (00:19:43)
Continuity mistake: When Indy abruptly brakes the truck and the Ark box slides backwards, the poles on either side of the box disappear for the rest of the chase.
Continuity mistake: When Marion gets off the submarine, there are two soldiers behind her. In the next shot, one of the soldiers has disappeared.
Continuity mistake: When the Wurffler arrives to Geheimhaven dock, six soldiers and an officer are running towards the submarine. In the next shot, the seven men have disappeared.
Continuity mistake: On the blackboard, between the numbers 4 and 5, the word "and" is written. After the girl shows the "Love you", the word is replaced by a dot. (00:13:49)
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.