Mutt's Harley sports a hydraulic master cylinder on the handlebar for the front disc brake. Neither appeared on H-D motorcycles until 1972. The "Softail" chassis like Mutt's came out in 1984. At least one of the bikes used is also equipped with an engine not released by H-D until 1999. It's clearly a modern bike with some window dressing attached.
On one of the soviet trucks used in the jungle chase scene, it shows external rear view mirrors in the 1970s style, which were identical to the type used on 1973 and GM pickups. This style of mirror did not exist in 1957.
Indy says that he and Oxley were obsessed with crystal skulls, in particular the Mitchell-Hedges skull, in college. Mitchell-Hedges claimed that his daughter unearthed the skull during a dig in 1927, but did not actually begin making that claim until 1943. This is after the events in all three previous films, and therefore, well beyond Indy's or Oxley's college years.
This movie is set in 1957. The gas masks used by the bio-hazard crew, while decontaminating Indy of radiation, are M-17 Gas Masks, which were not developed and used until 1959. Additionally, the M-17 mask is not designed for protection against radiation, making its use for radiation clean up incorrect, and dangerous.
At the beginning of the jungle chase scene, Indiana fetches a rocket launcher from the back of a truck and uses it against an armoured vehicle. However, this model - the RPG-7 - was not produced until 1961, four years after this movie takes place.
The refrigerator which Indy hides for protection from the atomic blast has the older type of door latch which cannot be opened from the inside. Later in the movie, one character calls refrigerators "death traps" for this reason. The shock of the blast rolls the refrigerator down into a gully, but the door remains latched until it stops moving. Then there's a click as though the latch is being opened, but there's no interior latch.
Many of the soldiers in the early scenes are armed with Thompson submachine guns (tommy guns). These guns fire from the "open bolt" position, meaning that the cocking handles would be locked to the rear if they were prepared to fire. All the guns shown have their cocking handles fully forward in the uncocked position.
In the transition-map scene when Indy and Mutt fly to Brazil the locations on Brazilian Amazon are appropriately written in Portuguese language but 'Río Juruá' is misspelled. In Portuguese the correct spelling is 'Rio' (without the acute accent on the letter 'i').
In the Area 51 warehouse scene Jones uses shotgun pellets to find a box with "highly magnetic" contents. All military issue buckshot pellets are made out of lead, and lead has no magnetic properties. Although Jones later finds out that the skeletons of the aliens attract non-magnetic metals, namely gold, it is unlikely that he would have tried to use lead to find a magnetic object before knowing this.
Indy says that the Nazcas elongated their skulls to imitate their gods. Actually the Nazcas didn't do that. The Paracas, a culture that existed in the same location but before the Nazcas, did, but for aristocratic reasons.
Indiana refers to the scorpion that attacked Mutt as having bitten him. Scorpions do not bite, they sting. Mutt said, "One of the scorpions just stung me! Am I gonna die?", to which Indy replied, "When it comes to scorpions, the bigger the better. Small one bites you, don't keep it to yourself."
Indiana says that the extraterrestrial will attract gunpowder because it's magnetic and gunpowder contains metal. In 1957, the U.S. Army was using smokeless powder, which contains no metal. Also, not all metals are attracted by a magnet: some are repelled by it.
When Indiana crashes the motorcycle in the Library he tells some students to look up Vere Gordon Childe because he spent most of his life in the field. Childe was not a fieldwork archaeologist, he worked out of museums. He did very little fieldwork in his entire career, he analyzed and catalogued the collections of various museums and was able to generate new revelations and discoveries because of his access to collections from around the globe.
In the scene where Indy and Mutt are in the café talking, Indiana is drinking coffee. When he sets down the mug the handle is pointed to Indy's left hand side. From Mutt's point of view the handle is pointing to Mutt's left hand side.
During the jungle chase (jeep vs. amphibious vehicle), in one shot, the pursuing vehicle is accelerating towards the other, the following shot, it is very far away, and in the third shot, it hits the fore-running vehicle.
In the car chase scene just after Mutt is swinging through the trees it cuts to a shot showing him looking at the cars colliding with each other. You can clearly see that Jones' car is on the inside away from the cliff and when it cuts back it's on the outside being pushed off the cliff.
While Mutt and Indy are in the chamber where they discover the crystal skull, Indy is holding the skull in his hands. During a series of cuts as they discuss the skull, it changes direction in Indy's hands, first the mouth is in his right hand, then it is in the left and back again, with no indication that Indy is flipping the skull during his conversation.
In the scene where Indy is walking along with Mutt, the position of the bags over his shoulder varies continually - in one shot his trademark gas mask bag will be hanging in front, then in the next shot it's behind his back and then in the next shot it's back in front again. This is made more obvious by the position of the buckle moving up and down as the bag is moved around.
When Mutt and Indy are in the diner, Mutt suddenly stands up and jars the table, knocking over the condiment bottles of ketchup and mustard. When the shot changes angles, the bottles are both upright again and when it changes back, Indy reaches out to right the bottles that are lying down again.
When Spalko is hanging from the tree above the ants, she crushes an ant between her legs squirting red goo all over her knees. A short time later you see her legs again and her trousers are perfectly clean - no ant body parts!
During the Title sequence, two different numbers are seen on the left front fender of the Ford leading the convoy of army vehicles. The complete number '1B7731' is seen several times. However, in the shot showing the driver's face in the rear view mirror, a number beginning with '2763' is seen (the full number is probably 276306). In a subsequent close-up of the Ford driver and passenger, the last two digits '06' are visible briefly at the very beginning of the shot.
In the tent scene, Indiana Jones tells 'Mac' that he's going to break his nose when he gets loose from his bindings. As soon as Mac lets Indy loose, Jones punches Mac in the face, breaking his nose, as promised. During the subsequent Jeep chase scene, however, Mac clearly has no injuries to his face.
Mac is first pulled out of the trunk of the car in the opening section. A couple of Soviets hustle him near the front right fender of the vehicle. In the next scene, Mac should still be near the fender, but he and the two Soviets are gone.
In the atomic bomb test scene Indy opens the refrigerator and pulls out the shelves before he climbs in. There is a small freezer compartment visible inside. After the blast that propels him and the refrigerator out into the desert the fridge door opens and he rolls out. In the first shot of roll the freezer compartment is still there and the edge of it is visible for about eight frames before being obscured by Indy's body, but in the close-up it has gone.
During the warehouse treasure hunt at the beginning of the movie, Indy uses handfuls of gunpowder and shotgun pellets to try and locate the highly magnetic item the Soviets are after. However, as soon as the box is discovered and moved, all of the light fittings within ten yards start leaning towards it. Given that wood is non-magnetic and hence would not have interfered with the magnetism of the item, the lights would have been leaning towards it even before it was taken out of the box, making the search a lot easier.
When Indy is first seen bound into the chair at the Soviet camp, the tape recorder supplying the music for the soldiers' party has played nearly all of its supply reel. When Spalko comes in for the interrogation, shortly after this scene, the supply reel has more, not less, tape on it.
In the jungle chase scene Indy, Mutt and Marion are tied up in the truck and they knock the guard out and escape. Indy is seen many times after they escape and Indy has no weapons. When he gets behind the wheel of one of the vehicles his whip is on his left hip.
In the jungle chase scene, in one shot Ox is sitting in the jeep's back seat, and nobody is behind him. But when Indy jumps onto the jeep, there are three soldiers sitting at the end of the jeep behind Ox.
Right before Dean Stanforth interrupts Indy's class to tell him that the FBI had ransacked his office and that he was being given a leave of absence, as he approaches the classroom he walks down a hallway filled with pictures and paintings. As they are leaving the classroom, in the hallway very close to the classroom door is a large painting of Marcus Brody, Indy's dear old friend and colleague. However, moments earlier when the Dean is shown passing by that same spot on his way to the classroom, the painting isn't there. In it's place are two indistinct photographs.
When a vehicle brakes suddenly, unsecured passengers are thrown violently forwards - a tactic used by Marion Ravenwood, at the wheel of a jeep in the jungle chase scene, to throw Irina Spalko forward on to the front of the vehicle. However, earlier on, when Indiana Jones and Dovchenko are riding unrestrained on a rocket sled, the massively greater braking force applied by the end-of-track water braking trough does not fling their bodies forward at all.
The arrival at the storage facility at the start of the film is in daylight, and Jones and Mac were taken inside in daylight, yet when Jones blasts out of the facility on the jet-powered sled - apparently not that much later - it is pitch dark outside.
When Mutt and Indiana Jones are on the motorcycle in the first chase, they go through the covered walkway that the car cannot follow them through. When the camera is looking from behind them you see a green car on the street when they are about to exit. But when camera is on the street when they come through it is a black car.
When Mut is driving his motorcycle along the platform while talking to Indy: In the shot taken from outside the train we see the train with Indy on it on one side of Mut and the station on the other. When the camera angle changes to a position inside the train behind Indy the station is gone and we see another train on the other side of Mut.
The aerial view of the Nazca lines shows at least 3 very close together. In reality the different lines are separated by quite some distance. There is also virtually no high ground from which to see the lines, i.e. at the entrance to the tombs.
The scenes in supposedly Peruvian towns feature Mexican music, dialect, and iconography, although Peru and Mexico are 3000 miles apart and have little in common besides the Spanish language. We even see a Mexican flag at the airport.
Buildings in the Nazca culture used adobe, not stone as depicted in the movie. Tombs were excavated in the ground, on flat areas, not on the top of the hills and the mummies were not wrapped in the fashion depicted with Orellana, but hunkered with the knees against the chest and then wrapped.
While supposedly in Nazca, Indy tells Mutt that he had learned "quechua" language while allegedly being kidnapped by Pancho Villa, as several of Villa's associates spoke it. Such language corresponds to the ancient Inca culture and is spoken in Peru, Ecuador, part of Bolivia and the Santiago del Estero province in Argentina. It is highly unlikely that any of Pancho Villa associates (Mexican revolution) would have spoken "quechua".
At various times during the movie, metal objects are seen sliding toward the skulls due to "magnetic" attraction. However, those objects never seem to actually finish their journey and reach the skull. This violates the laws of physics, because a large force is required to overcome the inertia of a body at rest. Once movement has begun, less force is required to maintain the movement, and the objects would accelerate toward the skull until they reach it.
When Indiana Jones is sinking into the sand pit, Mutt tosses him a snake and Jones uses it as a rope to pull himself out. Even a very large snake has a fragile spinal column. In reality Jones' weight should have torn the snake in half.
Despite popular belief, it is impossible to ride liana vines in jungles and/or rain forests by swinging and jumping from one to another, because they all grow from the ground clinging up - not at all in a dangling downwards way.
Leipzig, the city Indiana says he will go searching for a teaching position, was part of the Eastern Bloc in 1957, and it would not have been likely he could have been given access to a Communist country at this time. However, Indiana is joking, since he's accused of being a Communist.
In Indiana Jones and the Last Crusade (1989), Henry Jones drank from the cup of Christ, which was reported to give eternal life. In this movie he is said to have died. This is because he passed the seal on the floor where the grail was located. Once you cross the seal, you are no longer immortal.
When searching the warehouse, Indiana uses pellets from shotgun shells to help find the magnetic box the Soviets are searching for. Shotgun pellets in 1957 were made of non-magnetic lead. A later scene shows that other non-magnetic metals, such as gold, are attracted to the crystal skulls.
The movie places Orellana buried in a somewhat Nazcan fashion and in what supposedly is a Nazcan tomb. The Nazca culture was already extinct (aprox. 800 AD) when the Spanish Conquistadors arrived to Peru (1532 AD). However, Orellana was only looking for the city the Nazcas built, not the Nazcas themselves, and it is stated that he vanished while doing so. The movie is supposing that the Nazcas are not actually extinct, and that Orellana did find them and their city.
If the Crystal Skull were solid quartz, as explained early in the film, the characters wouldn't be able to hold or throw it easily with one hand. However, the skull isn't quartz. That's just an expression.
At the house at the atomic test site, the water doesn't run in the sink, even though water is running through an outside hose and sprinklers. Since the neighborhood was built to be destroyed, it doesn't have to be maintained perfectly.
Jones refers to the amphibious vehicles in the South American jungle as "ducks" (DUKWs) when they are actually Soviet GAZ 46 MAVs, copy of the Ford GPAs, or "Seep," for "sea-going Jeep." However, from WWII forward in the vernacular, "DUKW" has been a common term used for all unarmored amphibious military vehicles, whether this is accurate or not.
In the opening scenes when the Soviet infiltrators, dressed as US Army troops, gun down the guards, if you look at the Soviet on the lower left side, he's raking his machine gun back and forth even though he doesn't appear to be firing the gun (he's not pulling the trigger, no shell casings are ejected, and there's no muzzle flare). However, this is not necessarily a mistake. It is perfectly reasonable "cover" someone with a firearm, choosing to fire only when it's most advantageous to do so. Changing point of aim while assessing potential targets is likely consistent with his training.
It is shown that the Soviets use a large tree-chopping machine to go through the dense Amazon rainforest, however after the tree-chopper is destroyed the chase scene takes place on not one, but two very clear parallel roads out in the middle of the jungle.
At the end of the motorcycle chase scene through the library, the student's chair is pushed back. Initially, the student himself appears to push back with his feet, but the chair keeps moving well after he puts his feet back down. The floor is visible between the bike's front tire and the chair, so the bike is not pushing the chair. In the next shot, the tire is shown touching the chair. It isn't clear what the intent was (bike or student).
After the giant ant scene and Irina is hanging off the cliff by a rope with the other soldiers, a silver wire that is holding her up is seen leading down to Irina's waist right next to the rope she is holding onto. It is seen for only a few short seconds.
During the scene where Indy and Mutt drive the motorcycle through the library, it is clearly a stuntman and not Harrison Ford who slides under the tables on the motorcycle, as Indiana's socks go from dark (when it's clearly Ford on the motorcycle) to white (when Indy's under the tables) to dark again when Ford gets up on the motorcycle.
In the beginning when Indy opens shotgun shells to use the pellets he pulls off the primer end of the shell exposing the pellets. In a real shotgun shell on the bottom of the shell nearest to the primer is gunpowder.
During the car/motorcycle chase scene involving Indiana Jones and Mutt, Mutt slams on the motorcycle brakes so that Indiana, who is hanging precariously onto the back of the motorcycle, is flung forward back onto the motorcycle seat. However, the motorcycle is next to the car, and when Mutt slams on the brakes, and Indiana is flung forward, the car and the motorcycle remain moving at exactly the same speed. The car should have moved ahead of the motorcycle when the cycle's brakes were applied.
When the tribal person is about to shoot Mutt with a blow dart, Indiana Jones comes from in front and blows the dart the other way through the pipe, killing the person. It would have been the blunt end and would have had no poison on it.
The goof items below may give away important plot points.
When the skeletons of the Inter-Dementional beings are coming together as one, only 11 of the skeletons are shown combining with the first. This makes 12; in previous scenes however, it is stated, and shown that there are 13 of these creatures. Which thus, leaves us all to ponder the question: What happened to the 13th alien?
The cemetery where Indy finds the Crystal Skull is revealed on a mountaintop overlooking the Nazca Lines during a thunderstorm. There are no mountains close enough to the plains of Nazca to allow for such a view as shown. Also, being an arid desert, there is no weather to speak of (wind or rain, much less thunderstorms) in Nazca, which is the reason why the drawings have not been eroded over the centuries.
Marion tells Indy that Ox stopped speaking to him for leaving her a week before the wedding. If he knew them when they planning to get married he would have known that Mutt was Indy's son, yet when Mutt calls Indy "dad" he seems surprised. However, we do not know when Marion became pregnant with "Mutt". Marion herself may not have found out until after Indy left.