The number plate of one of the vehicles in the "Madrid" scene ends with a single A. The other one has just numbers and no letters (apart from the M, standing for Madrid). These are very old number plates for 1981 Madrid cars (at least, 15-20 years old) and the looks of both cars are way too new to accept they had such numbers. Most likely, they would have plates ending in two letters (in 1981 the plate letter series had gone already as far as EP).
The sound of the diving helicopter when 007 was attacked at the beginning, and again with the attacking seaplane, when Melina's parents were killed on the yacht, is that of the Junkers JU-87 dive bomber, or "Stuka," and not that of a helicopter or seaplane.
When Bond and Melina are to do the deep dive Bond mentions that they must use a mixture of helium and oxygen but when they communicate through the helmet radios, their voices sound normal, not high pitched like it should be.
When Bond is standing under the arch, and shooting at Locque's vehicle, he fires one shot. A bullet comes out and hits the windshield. A second later, another bullet hits the windshield, but there was no sound of a second bullet being fired from Bond's gun.
During the car chase, Bond says "Take the low road." Melina's car gets flipped over, with Bond and Melina inside, Bond says something like "not THAT low." However, his mouth keeps moving as if he is saying something else, but no words are coming out.
When Melina removes her scuba helmet after diving for the device, there is a release in pressure. Her air tube had already been punctured by the bad guy, so the pressure was already released and therefore no sound should have been emitted.
When James Bond and Melina are walking in the streets, some salesman hands them two figs to eat, and Bond says "Parakalo" (which means please or you're welcome) before receiving the figs. He says it after the man gives it to him, which should be followed by him saying "Efharisto" (thank you). The only reason it would make sense for Bond to say "Parakalo" afterwards is if he said it to Melina as a way of inviting her to try a fig, but he says it directly to the salesman.
When Bond and Melina leave their sub to retrieve the ATAC, Bond tells Melina to speak only when necessary to reserve their air supply. But during their trek to the ship wreck and when Bond is disconnecting the ATAC, he does a lot of unnecessary speaking, such as reading the ATAC disengagement instruction card aloud to Melina, even though he's the one doing the job.
When Emile Locque's bibliography appears on the Identigraph screen, the first appearance of the word bibliography is misspelled "BIBLOGRAPHY". The second appearance, near the bottom of the screen, is spelled correctly.
When Bond and Melina are dragged under water behind Kristatos' yacht, in one shot Melina's swimming suit has slipped down showing her naked bum. In the next shot it is back in place while her hands are still tied so she couldn't have done it herself.
When the mountaintop monastery guard is struck by Bond's piton, the blade enters his chest dead center, a few inches below the adam's apple. Yet when the body lands on the ground, the blade has moved to the man's left shoulder.
When Bond is climbing up the rock towards St. Cyril's, he anchors his rope to a spring-loaded camming device, and subsequently drives pitons into the rock as he goes. When the henchman has dislodged all the pitons so that Bond is swinging from one final anchor - the first one he placed - that anchor has changed from a spring-loaded camming device to a piton.
When Bond's/Columbo's infiltration team surprises the dorm full of off-duty guards at St Cyril's, a blond man seen briefly rising from a bed on the left is the same guard the team already dealt with on duty outside - he was last seen tied up and gagged after being shot with an arrow, then knocked unconscious in the basket room a few minutes earlier.
When Bond and the countess are being chased on the beach, one of the dune buggies loses its passenger side headlight. Moments later, as Bond foot kicks the gun out of Locque's hand, the headlight that was dangling from the car moments before is now securely back in place.
Bond races through the ski chase with only one ski pole (the other was damaged by the sniper chasing him). The remaining pole was used to clothesline one of the bikers following him, but he has it again in the later shot when he first approaches the bobsled track.
As Bond climbs up through the forest to the pool party, the guard is distracted by a woman with long curly brunette hair and a red flower over her right ear; she is wearing a blue bikini and a long cover-up. After Bond passes her and the guard and proceeds up the hill to spy on the pool party, this same woman is now seen dancing at the party in the first shot seen through Bond's binoculars; she could not be in both places at once.
During the downhill chase when one of the Peugeot 504s begins to bump into Bond's 2CV, We see a close-up of the driver and there are no vehicles visible on the road behind him. In the following shot when Bond is pushed off the road the second Peugeot is almost directly behind him.
When Bond and Melina exit the sub, the beam in their flashlights is red. When they get into the sunken St Georges (another set) the beams are clear (white). When they return to the sub, a brief view of the flashlight beam as the light falls to the ocean floor again looks red.
The amount and placement of damage to Melina's car changes many times during the chase scene. For example, at one point, the entire front hood of the car is smashed in pretty bad, but near the end, the front of the car is only mildly damaged.
During the fight in the ice rink, one of the hockey players tries to kick Bond with his blade. He puts his foot through the wall. When it cuts to the next scene, there is no damage to the wall in that spot.
When Bond and the diver are fighting over the ATAC, Bond is holding onto it with his left hand. The diver sends Bond crashing through a glass window, and it cuts to the next shot. Bond is now holding onto it with his right hand.
When Bond is being chased after the ski jump sequence he skies past a "beginners class" who all fall down after he passes. The last person to fall over is a woman with distinctive striped tights/pants. The next scene shows Bond skiing towards the camera and he passes the same woman, skiing. Then the shot changes to show him skiing away from the camera and she's there again in a different position, but this time with a different jacket and different hairstyle.
During the ski chase, Bond jumps over the two henchman shooting at him, causing the Klaus character to fall over. As he does so, his motorbike falls too, but is back upright again immediately as Kliegler skis over them.
When the Citroen is going downhill in the chase scene, the front right headlight is smashed and reveals the yellow paint inside the headlight pod. Just before the car reaches the road at the bottom of the hill we clearly see the broken chrome reflector.
When the Neptune is hauled aboard and Kristatos starts talking, his yacht is a decent distance away in the background, moving slowly. Yet, a few words later, after a shot on Bond & Melina, it is suddenly much closer at apparently the same speed and without a change of wake.
In the final scene, Bond's superiors call him using his radio watch. As it signals him with "Come in 007", the time on the watch is around 9:20. Moments later the parrot drops it into the water and it is shown sinking; the time on the watch now appears to be around 11:55.
Near the beginning of the movie, when Bond and Melina are chased from the pool party, a near perfect reflection is shown in Melina's window of a crewman holding a yellow pole with equipment on top and wearing a short-sleeved tan shirt and black glasses. A few frames later he waves his hand between the backseat window and the camera.
Whilst inspecting the sunken fishing boat for the ATAC console, Melina is pulled up by a henchman in a white diving suit, there is a cable and hook quite visible on the back of Melina's diving suit winching her up the wall.
During the dive on the sunken sub, it is stated the pressure is very great requiring special suits. One of the bad guys is using a JIM Suit, which is designed for extreme depth dive work. Yet when they emerge from the sunken sub the water is very light blue and the color rendering is very good. This is only possible in 1 Atmosphere diving. At depths below 100 feet the water is very dark and colors are very gray.
Bond and Melina are chased by cars in the mountains near Madrid, Spain. Yet when one of the pursuing cars falls down a cliff and into a net where olives are being harvested, the farmers can clearly be heard swearing and talking in Italian, not Spanish.
James Bond and Melina first meet in a house which is supposed to be in a mountain area near Madrid. There are women wearing bikinis and a swimming pool. In the meantime, some farmers are harvesting olives near there. Olives are harvested in December-January, when temperatures around Madrid are around 5 degrees Celsius.
That the helicopter was remote controlled would not have nullified the input given by 007 after he assumed the cockpit. In other words, James would still have been able to control the helicopter, although it would have conflicted with the input (radio control) of Blofeld; the radio control itself does not physically interfere with cyclic control stick of the helicopter.
Colombo calls St. Cyril's an abandoned monastery, yet it has a modern helicopter pad. He says Kristatos has made it his personal retreat. Obviously it has had electrical power, the basket winch and helipad installed when he converted it to his fortress home, along with bringing in items such as a gym for Bibi.
During the keel-haul sequence, Bond and Melina are bleeding profusely but the sharks take no notice. As soon as the henchman falls in the water (who does not appear to be bleeding), two sharks appear and eat him at once. The sharks clearly have a moral compass.
At the baccarat game, Bond has the same cards for both the first and second hand; the queen of spades and the five of diamonds. While this is, strictly speaking, not impossible (several packs are mixed together to fill the shoe from which the cards are dealt) it is blindingly unlikely, and the fact that these cards are initially erroneously described as giving a count of nine (court cards and tens count nothing in baccarat, while number cards count for their respective number of pips) makes it far more probable that the close-ups of Bond's cards are in fact both taken from the second hand played.
During the fight in the hockey rink, Bond climbs into the Zamboni and "hits" the last hockey player. These machines are very slow, and don't get powered up very quickly. When you look closely at the footage, it seems more like the hockey player literally skates head-on into the Zamboni on purpose.
The third time the ATAC officer reaches for the destruct switch, his thumb catches the destruct charge and flips it up about an inch, despite the fact that it's supposed to be fastened by a very strong magnet.
While Bond is climbing up to the monastery and he reaches the top, the camera shows the anchor pulling out of the cliff. It is obviously stop motion photography because rocks disappear and shadows move very jumpily.
Bond and the diver are fighting over the ATAC. Bond gets pinned underneath some type of machine. The diver reaches down and cuts Bond's elbow with his claw. If you look closely, Bond's elbow is already cut and bleeding before the claw even makes contact.
After the car is kicked off the cliff, a dummy (representing the character inside) falls out of the car window when it lands. After Bond says his line, we cut back to the car, this time from above. The car is in a different place with the dummy where the car should be.
When James leaves the sunken ship after escaping from the attacker, you can see that his dive helmet suddenly has an inner black mask attached, covering his mouth and nose. It's a stunt diver. (Those dive helmets usually have an inner mask preventing CO2 poisoning - but obviously you wouldn't have been able to see the actor's faces then)
In the opening sequences where James Bond has taken control of the helicopter from 'Blofeld' and is carrying him aloft in his wheelchair, at one stage the stunt man in for 'Blofeld' is replaced by a dummy. Immediately after, the stunt man is back in the chair and it's obvious he's wearing a 'bald wig'.
When Melina and Bond return to the sub and expel the water from the airlock, Melina is gasping for air, and she grabs the regulator and breathes. There is no need to use the regulator as the airlock is already full of air.
The goof items below may give away important plot points.
When Gonzalez jumps off the diving board into the pool, there is the sound of an arrow but no arrow actually hits him. In the next scene, the arrow is in his back. At the time he was hit with the arrow he was parallel with the water in the pool; thus, this would mean he was shot from above, a complete impossibility.
When Melina and Bond are being dragged behind Kristatos' yacht, Kristatos is briefly seen keenly looking aft, towards Bond and Melina. After they manage to cut the rope and the yacht has turned around in order to run them over, Kristatos is again seen in exactly the same pose, still looking aft, which will now be in the exact opposite direction of Bond and Melina.
When Gonzalez gets hit with the arrow, this scene is filled with errors. First of all, when he hits the surface of the water, it plays the sound effect of him getting hit by the arrow, but there is no arrow in his back. It cuts to the next shot, and not only is the arrow in his back (in the wrong spot nonetheless), but there is also dried blood. If he just got hit, it makes no sense for there to be dried blood already, especially underwater.
After Melina and Bond have managed to cut the rope that was used to drag them behind Kristatos' yacht, Kristatos orders the helmsman to run them over. The yacht is a Panther, typical for the time, with a squat, planing hull with hard chines, some 5m wide and 20m long, with an almost rectangular "footprint" in the water. When Bond and Melina dive and look up at the passing yacht, it is a completely different vessel, with a slender and much longer round bilge displacement hull, probably a pilot boat or a military patrol vessel.