Goofs

(at around 1h 45 mins) While the ambulance is inside the parking garage, Neil takes his surgical gloves off twice and throws them into the trash bin.

(at around 57 mins) When the Protagonist, Kat, and Sator are on the racing boat, they start to cross to the other side of the boat for balance after a turn. However, the next shot shows them arriving at the same side of the boat they started at.

At the end of the protagonist's encounter with the masked man moving in reverse inside the Freeport at Oslo, his opponent exits the storage through a damaged shutter which mostly heals up, but remains partially damaged. When the masked man returns to the same time and scene while moving backwards in time, the shutter is intact before he enters the storage through it. The shutter couldn't remain partially damaged after the masked man exited through it in the first encounter, since it would be in the state before he affected it.

(at around 2h) One of the Red Team soldiers can be seen moving backwards even though the rest of the team is moving forwards.

(at around 57 mins) When Sator, Kat and the Protagonist are on the racing boat, Sator speaks to the Protagonist through the microphone attached to his helmet, before manually adjusting the microphone to be placed in front of his mouth.

The small air cylinders or point bottles have a very limited capacity of between 450-900 liters of air, enough for an average adult to breathe for, at most, two and a half hours with little or no physical exertion. Running, moving heavy objects, fighting or engaging in a gunfight would deplete their available air in mere minutes, far less time than is shown.

(at around 37 mins) At the airport in Oslo, the roof-mounted sign contains a misspelling of the Norwegian word for "exit". The sign says "utång" rather than "utgang".

(at around 49 mins) The newspaper that Priya shows the Protagonist regarding the Oslo plane incident is dated Friday June 12, 2019, but June 12, 2019 was actually a Wednesday.

(at around 52 mins) Kat tells The Protagonist that the yacht sleeps 70 aboard. In fact the yacht used for the movie, M/Y Planet Nine, accommodates fewer than half that number. The yacht normally carries a crew of 20 and a maximum of 12 guests.

In the scene where there is a 747 being towed and then someone at flight deck takes over the controls...

This cannot be done in real life since when an aircraft is towed there is something called a bypass pin installed that prevents flight deck from steering. This is an actual pin that would have to be removed physically to start steering from flight deck.

(at around 1h 40 mins) While Neil and the Protagonist are trying to get into the Freeport in Oslo with injured Kat, the explosion from the aircraft's engine appears to push the Protagonist into the building in inverted time. However, it is actually the engine reforming that causes this, as in non-inverted time the engine is sucking air in, meaning it is suddenly blowing air towards the Protagonist in inverse time.

In the lab when The Protagonist is learning about inversion and firing the gun the scientist mentions the bullets came with the wall fragment. How can the inverted bullets be caught by the gun and magically get a bullet casing in the magazine? An inverted casing would have to be nearby and fly up into the side ejection port to merge with the projectile. And in fact viewers briefly see a bin of casings parked next to the firing range, which is where the first casing came out of.

(at around 1h 30 mins) The Protagonist asks for the device to track the transponder in the case that they stole from the truck (that supposedly had plutonium in it). However, at this point, the Protagonist is inverted in time. Which means from his point of reference, the radio waves that are normally emitting from the transponder are actually traveling backwards into the transponder (so from his inverted point of view, the transponder is sucking in its signal, not emitting a signal). So he shouldn't be able to track the transponder with a normal tracking device. (Of course, if he is being supplied with tech from the future, which is not indicated, anything is possible.) However, regardless of how a normal tracking device works in reverse time, what matters is that it simultaneously "co-exists" in regular time, where it would work normally and display information on the screen which would be visible both in regular and in reverse time.

At the beginning of the movie, the Protagonist sees an inverted bullet fly backwards through a person in real time, causing damage in real time. Later, he sees an inverted bullet fly backwards through a glass window and "heal" it in real time, meaning it caused damage retroactively. This is contradictory and they cannot do both. Unless the glass is also inverted, this scene breaks the movie's own rules about reverse entropy. However, it actually doesn't. The glass was shot with the bullet in reverse time and then it "healed" in real time because the bullet "undid" its own effect when it came into contact with the glass a second time. When the inverted bullet passes through the person at the start of the film, it caused damage because this was the first time it had come into contact with that person and no prior effect could be "undone".

It is established that going backwards requires an external breathing apparatus, but Kat does not wear one at any point while on the boat with Andrei. Kat at this point is experiencing time normally, alongside Sator and the yacht's crew, she inverted at some point on the tenet ship and was taken to Vietnam. Protaginist referenced this when the soldiers were inverting and he told Kat to keep going another day, presumably this is when she deverted.

When the Protagonist is fighting the masked man (himself) the first time just before he threatens to shoot him, the masked man's wrists are exposed for a short time and they can be seen to be white.

On many occasions during the movie, some characters are manipulating gold bars too easily relatively to the gold's density. The larger gold bars from the plane scene weigh about 20kg (about 45 lbs) and would not be easily picked up with one hand. The smaller bars from the crate would weigh about 5kg (about 11 lbs).

When Mahir and Rohan are hijacking the cargo plane, Rohan decides to boost a gold bar for himself. He easily removes it from within the cargo netting where the stacks of bars are stored. For obvious reasons, such heavy cargo would be stowed very securely to prevent shifting during flight. If Rohan can simply reach through the netting and remove a bar, then the bars could shift during flight, with potentially catastrophic results.

(at around 1h 30 mins) When the Protagonist inverts himself and drives the Saab, he initially drives it in reverse gear to go forward. A moment later the car slows down and the tires roll forward, which means he is driving normally.

When the freight plane is crossing the courtyard on its way to impact, its engines are running, as planes move forward using that thrust - there are no drives for the wheels, like a car. All litter and things on the ground in the plaza would be sucked up into the engines - the same for the twigs/leaves off the trees - probably gumming up the engines and stopping them.

(at around 6 mins) When the Russian on the van says "It's not the man" (right after the opera siege), you can clearly see that the van isn't moving. You can hear the sound of an engine that is accelerating, but it's clearly a mistake.

When the Protagonist enters the private room in the opera house where the Well Dressed Man is, he shoulders his weapon and fires two shots from his rifle. The first gunshot hits the armed guard, but the second gunshot isn't heard until after his rifle is unshouldered and already pointing at the floor.

(at around 1h 30 mins) When the Protagonist enters the Saab, hands can be seen in the wing mirror.

(at around 1h 24 mins) A reflection of the film crew's dolly can be seen on the lower left corner of the glass.

(at around 1h 40 mins) A shadow of the crew's light fixture is visible on the ambulance when it drives off.

Due to reverse heat transfer, all inverted people should freeze to death under the sun.

Time-reversed characters must annihilate upon contact with any non-time-reversed matter, not only themselves, for the reasons explained in the movie itself: on quantum level laws of physics are time-reversible but reversal of time for any particle is equivalent to turning it into anti-particle, and anti-particles annihilate upon contact with particles.

When they are inverted in Oslo, they choose at random an ambulance to commandeer. Such ambulances need special modifications to be airtight. They are not seen to make special allowances for inverted air, but later on Neil moves to the front of the ambulance without a mask and joins the Protagonist, who is also not wearing a mask.

Protagonist asks for an "expresso". There is no such word. The correct word is "espresso," which refers to water being forced through coffee at a high pressure. A man as well educated as Protagonist would know this.

After defeating his masked future self in Oslo, the Protagonist interrogates him, speaking normally. At that point, the Protagonist knew about inversion and would know that the masked man would hear him talking backwards and not understand him.