Goofs

Grace crawls over the coals on the train. For the rest of the movie, her shirt is completely unmarked with any coal stains.

During the chase scene in the small yellow Fiat, Ethan tells Grace "left left left" to make a left. Grace makes the left and audience see a black car parked on the right side of the street which Grace barely misses. Seconds later, Paris, who is chasing Ethan and Grace, makes the same turn but now the black car is gone.

When Grace (as The White Widow) slides the two halves of the key across the table to Kitteridge on the train, her hands and nails are clearly visible - her nails are cut quite short, with shimmery polish. A scene later, when Grace has removed her mask and puts her hands up, her nails can be seen extending beyond her fingertips.

When Ethan enters the train with a parachute he breaks the window but in the next frame there are no glass pieces.

At the beginning of the "The Austrian Alps" sequence, the number plate on Benji's BMW is Swiss. At the end, when he picks Ethan up, the plate is German.

The Orient Express uses electric and diesel locomotives provided by the local railroad, and does not use coal.

When Grace (masked as the White Widow) is receiving $100m worth of cryptocurrency from Kittridge, the screen says "decrypting blockchain." Transferring cryptocurrency simply requires sending tokens from one wallet address to another, a transaction that is written in a blockchain. It does not involve encryption or decryption of a blockchain. In addition, the empty entry field is marked "IBAN" which would not be used in a crypto transaction.

The super stealth submarine at the start of the film was continually transmitting active sonar pings, which would immediately give its position away to every ship and underwater sensor within several miles.

Would be impossible to uncouple the engine from the coaches while the engine is fully pulling the train.

The Orient Express does not travel from Venice to Innsbruck. The current Orient travels from Paris to Vienna via Munich. It did run Paris to Istanbul via Venice from 1919-1939 then again from 1945 till 1977. Thats the train Agatha Christie wrote about.

Steam trains, especially moving at high speeds, need to be continuously provided with fuel, in this case coal. With the engineers killed and the controls opened all the way, the locomotive would have gradually slowed down and come to a halt as the pressure in the boiler dropped. That train would never have reached the bridge for that distance with no coal provided.

Since the early 1900s, when firebox coal consumption exceeded the efforts of two men, the trains have used mechanical stokers. The coal would continue feeding without one missing coal shoveler.

Obvious gas explosions at the NSA and yet no security or phone call for 10 min.

Top-secret NSA unexplained (they didn't know it was gas) explosions required checking before emergency people rushing in.

Denlinger says that the biggest problem in security is the "human factor" yet he set up a massive room full of humans reading and manually copying top-secret records.

However, the massive amount of records that needed to be copied could only be done by hundreds of people. Given the stakes involved, it would seem to be a reasonable and even necessary risk to take.

When the yellow Fiat rolls down the stone steps and lands upright there are no dents or scratches to the car. However, the car is clearly highly modified ( palm reader, self-driving, much higher power ) compared to the original ; so it may well also have a much stronger roof.

Simon Pegg tells Tom Cruise "she's heading toward the bridge"--in Venice, where there are 391 bridges. However, he also says "she's straight ahead of you", suggesting that bridge is the nearest one in that direction.

Hunt slams Paris' head against a block wall to knock her out of the alleyway fight. The following day on the train, Paris has no bruise, scratch or any mark at all on her face/head.

In the train fight sequence, the camera captures the train from the side with both Ethan and Gabriel standing at the top of the train, and the train is visibly running very slowly, whereas, at this time, the train is supposed to be running at full throttle, at a high speed.

Venice is a densely populated city and major tourist destination but is depicted as completely deserted other than the people directly involved in the film's events.

No impact of bullets on the dead bodies for the mercenaries in the desert.

When Gabriel leaves the baggage compartment smoke blows over his shoulder to suggest movement of the train, but the sky above him doesn't move, showing he's on a set.

The train cars continue to fall over the end of the bridge, despite the fact that most of the cars weight is clearly on the bridge.

After the engineer is thrown off the train. And the controls are smashed and disabled. The train whistle continues to sound, several times.

Correction: @1:53, he hangs the conductor on the whistle rope and sets off the whistle moving the hanging body. The body swinging around sets off the whistle.

When agents arrive at the police station in Rome, they are in a bmw 5 series g30 when they leave to chase Ethan car changed to a 5 series g30 facelift.

When Ethan Hunt met with India-Zulu-254 he said, "Welcome the IMF." That's a grammatical error. But the English subtitle shows the correct form: Welcome to the IMF.

Alana has blue eyes. When Grace put mask and become Alana, she had brown eyes. Alana' s right hand man didn't notice and the IMF head man too. They looked at her face more than 5 minutes. Especially Alana's blue eyes are so different that is impossible her right hand man would not miss.

They create a mask for Grace but not a voice modulator.