Continuity mistake: At the very end of the movie, when they all ride off through a tunnel, you can see all sorts of tassels hanging off each of the horses. When they reach the end of the tunnel and are riding off into the sun, there are no tassels at all apparent.
Other mistake: At the library in Venice, Brody and Jones point out the Roman numerals in the library, wondering what they mean. Elsa comes over, and they show her. In front of her, behind the rail, is an obvious plate of glass. You can see her reflecting in it. The plate disappears in the next shot and never returns. The plate is not there in the longer shots. Where did it come from?
Suggested correction: I just watched the scene about five times and could not find any glass or reflections. All I saw was their shadows against the wall. Furthermore, it would make no sense for them to set up a big glass plate for one shot and only one shot.
I re-wound it several times. It's right at the beginning of the shot when Elsa comes from the right. It's brief but there. This was on a TV version. You may be watching a fixed version on DVD or Blu-ray. I'm sure the mistake has been corrected in later releases.
I think you are mistaking a shadow for a reflection. Or possibly it's just a video artifact. As the previous correction stated, why would there be a sheet of glass there?
I'm standing by my correction in this case. It just patently makes no sense why they'd set up a big pane of glass on their set for one shot then remove it. It wouldn't serve any purpose other than to catch light, and it would have also lightly messed with the way the background looked and the shadows the actors are casting. If it was a TV version, there's no way to tell what master they're using, how old it is, how it was stored, etc. It could have video artifacting or damage that caused the "reflection." (Probably just a light "ghosting" effect.) Heck, sometimes even your TV settings can cause issues like that. If you use any sort of motion smoothing or frame interpolation, those can create weird double images sometimes because the software doesn't always work properly.
Continuity mistake: In the library before he goes through the hole in the floor, Indiana takes the map out of the diary and gives the diary to Marcus. When Indiana gets caught trying to rescue his dad, they take the diary from him and say Marcus has the map.
Suggested correction: You've forgotten the scene at Donovan's apartment. There, Indy could have cut the page and give it to Brody off-screen.
Revealing mistake: In the shot of Elsa falling to her death into the misty chasm in the Temple, you can see that it is not Alison Doody but a stunt double.
Continuity mistake: The blood on Indy's left ear disappears at the end of the film.
Continuity mistake: When Indy kisses Elsa in her room in Venice, you can see there is nothing on Elsa's left shoulder, but when the camera angle changes in the next shot, Indy now has his hand on her shoulder.
Visible crew/equipment: In the catacombs after Indy passes the picture of the Ark Of The Covenant and approaches the next wall with the lighter, (when the screen goes upwards a bit) the shadow of a boom mic can be seen dropping into view at the top of the lighted wall. (00:31:40)
Continuity mistake: Indy slams a pole against the big X on the floor and produces a hole. When the angle changes the shape of the hole is completely different.
Revealing mistake: When the tank shoots-up the jeep the interior is revealed to be empty and such a prop.
Continuity mistake: While in the zeppelin, the German officer extends his baton and lowers Dr. Jones's newspaper, wrinkling it. From the opposite angle, the newspaper is still raised and the officer repeats the previous movements, though this time he doesn't wrinkle the newspaper.
Continuity mistake: Hitler walks surrounded by a huge crowd ahead holding Nazi pennants. When Indy bumps into Hitler, half a second later, the pennants on the left have disappeared.
Continuity mistake: Dr. Jones hugs his son and walks 20 meters away. When he turns around to address him, he is barely 5 meters away.
Continuity mistake: When a jeep gets stuck to the tank's cannon, the type of jeep, its position and the damage done changes between the first and second shot (watch how the smashed windows fix themselves, for example).
Continuity mistake: In front of the main tribune there's a pile of burning books. First the fire is just atop, a frame later the whole pile is burning.
Continuity mistake: When Indy jumps on Kazim's boat, Elsa's boat is inches away from Kazim's, but a shot later she has managed to appear somewhere else with no boats around.
Continuity mistake: When about to walk on air in the temple, Indy says, "No one could jump this". In the close-ups his hands are spread apart, but in the wide angle they are grabbing the diary.
Revealing mistake: Dr. Jones fires at the jeep from the tank, but the explosion doesn't come out the cannon, nor by the jeep's window next to it; instead the back of the jeep explodes.
Continuity mistake: The German Nazi suddenly disappears from the tank when it crashes on the ground (as is replaced by an obvious scale model).
Visible crew/equipment: After Dr. Jones is healed, Indy tells him to stand up. Stage lights are reflected in Dr. Jones's glasses.
