Goofs

(at around 1h 1 min) While on the Maw's spaceship, Tony Stark, Peter Parker and Dr. Strange's cape have a conversation. and for the entire scene Peter's hair is slicked back. During an intense exchange with Tony, Peter says "You can't be a friendly neighborhood Spider-Man if there's no neighborhood"; the camera cuts to a speechless Tony and then goes back to Peter, who now has a completely different hairstyle, featuring a fringe. His hair turns back up for the rest of the scene.

(at around 12 mins) The first time we see Tony Stark, he is walking with Pepper Potts in a park, discussing. Tony has a hoodie on his shoulders, its sleeves tied in a knot covering the miniature arc reactor on his chest. During their exchange, Pepper unties the knot to talk about the device on Tony's chest. Right after that, cutting from a three-quarters shot to a close up on Tony, the hoodie disappears and is nowhere to be seen for the remainder of the scene, up till the moment we are taken inside the Sanctum Sanctorum.

(at around 23 mins) During the New York confrontation, when Ebony Maw strangles Dr. Strange and he falls down, he hits a cop car next to him. In the next scene, when Ebony Maw lifts the ground around Strange, the cop car is nowhere to be seen.

(at around 25 mins) When Peter falls from the spaceship in the upper atmosphere, the rocket containing the Iron Spider suit makes contact with his back and the suit begins spreading outward. The spider on the back of the suit is visible in one shot, then in the next shot, it shows the back forming (even though the back was the first part to form).

(at around 23 mins) When Ebony Maw wraps the electrical cable around Strange, he loops it several times around his neck to make him pass out. Immediately after, the cable is no longer wrapped around his neck, allowing his cape to fly him away. The cable is also tightly wrapped around his body, and then loosely wrapped around it in the next scene.

(at around 18 mins) When an emergency exit on a school bus is opened, an alarm goes off. Peter would not have got off the bus quietly.

When Spider Man falls away from Ebony Maw's ship, he should have been left behind by it almost instantaneously as it was accelerating to escape Earth's gravity. Even if Tony Stark's Spider Armor caught up with him, it still should have met while he was falling away from the ship and not been able to save his life in the manner that it did,

Spider Man is shown adhering to Ebony Maw's ship as it leaves Earth's atmosphere. To escape Earth's gravity ,especially since it's ascending directly into space and not using the planet's gravity to assist it , then it would have been traveling at tens of thousands of miles per hour.

Spider Man, even with his strength, would have been injured by the acceleration of the vessel, if not outright killed well before he lost consciousness due to the lack of atmosphere and the cold temperatures.

(at around 1h 15 mins) When Thor goes to Nidavellir, Eitri tells Thor he made the gauntlet for Thanos because Asgard neglected to protect them. Asgard was just destroyed prior to the first scene of this movie, and yet the gauntlet was shown at the end of Avengers : L'Ère d'Ultron (2015), which takes place years prior. However, recall that Loki had been ruling Asgard for four years (overlapping Age of Ultron), and had allowed the Nine Realms to fall into war and chaos without doing anything on his own part to protect them (as opposed to Odin always striving to protect his kingdom). Loki's neglect would have most certainly left Nidavellir exposed to an attack from Thanos (assuming that Thanos obtaining the gauntlet in Age of Ultron is chronologically correct), which may be what Eitri was referring to.

In Les Gardiens de la Galaxie (2014), Gamora is described as the last living member of her species. However, this is only seen on a display in the prisoner status scene when introducing the GOTG. In this film Thanos is shown to have killed only half of her planet's population. Even Thanos tells her that life has been better for those born on her home world since his genocide.

(at around 1h 30 mins) In Black Panther (2018), when King T'Chaka shows up at the beginning, N'Jobu and James (Zuri) bow before him to revere him as a king. In this movie, however, Bruce Banner attempts to bow before King T'Challa, who then states "We don't do that here." However, in the same movie, when Shuri bows for T'Challa in modern-day Wakanda, he recognizes this as a joke and tells her to stop. This could suggest that he had changed reverence policies since his father's reign.

(at around 21 mins) When Tony Stark first uses the nano tech to put on the Mark L armor he takes off his shades with his right hand. As the armor finishes you can see the shades disappear from his right hand. Fully formed his right hand is still holding the now non existent shades. However, this is not a mistake. If you pay close attention to the glasses you will see that the shades are actually nanobots that are absorbed into his suit.

(at around 11 mins) When Banner falls through the roof and the stairs Doctor Strange is wearing street clothes. As he runs up the stairs and dons the cloak the rest of his clothes change to his typical outfit. If you watch carefully when Strange heads upstairs, from behind you can see his clothing change from street clothes to his "duty uniform" as the cloak settles on his shoulders.

(at around 17 mins) When Tony, Bruce, Dr. Strange, & Wong leave the Sanctum a car crashes into a pole. You can see the car is already damaged before impact.

(at around 1h 40 mins) During a close-up of Black Panther, when he gives the order to open the shield, his suit has clearly visible seams on his shoulders, giving it away as a spandex costume.

(at around 16 mins) When Tony Stark is deciding whether to call Steve Rogers or not from the Sanctum Sanctorum, the green screen used on set is seen reflected in the screen of Stark's flip phone.

(at around 2h 20 mins) According to the end credits, one of the production units filmed both in the United Kingdom, and in Scotland. Since the United Kingdom includes Scotland, that would be like having a unit that filmed both in the United States, and in Missouri.

(at around 1h 3 mins) At Ebony Maw's ship, Dr. Strange questions Iron Man if he can disconnect the automatic pilot and drive the ship to back planet Earth. It's a nonsense question for Strange since that he wears his double-ring to create space portals, being capable to back planet Earth at any moment. In fact, at around 1h 48 mins he uses it during Titan's battle between him, Iron Man, Spider-Man and Guardians of the Galaxy against Thanos. In addition, in Avengers: Endgame (2019) during final battle against Thanos at around 2h 16 mins, a countless number of portals are created by several sorcerers to reunite all superheroes to fight Thanos and his armies, including one opened by Dr. Strange to return from Titan to planet Earth with Star-Lord, Mantis, Drax and Spider-Man.

Thanos and his henchmen find the Infinity Stones at once, like they somehow 'felt' their exact location. If they did, then Thanos shouldn't need Gamora to find the Soul Stone. If they didn't, they shouldn't appear right where Vision and Dr Strange are with their respective Stones.

Thanos' premise that there is too much life for all the resources of the universe leads him to think the solution is to remove half of all life in the universe. A much better solution for someone who has god-like powers is to simply provide greater, if not infinite, resources than all life in the universe can possibly use for all time. This would eliminate the need for all of the bloodshed he has caused.

Thanos claims that by eliminating half of all life in the universe, the rest who survive will be able to live better because there will be more resources for them. Thanos doesn't realize that this is a temporary solution to his so-called problem. Life will simply expand again to previous levels in a relatively short time.

(at around 34 mins) When Thor is explaining to the Guardians of the Galaxy where they need to go to forge a weapon to kill Thanos, he pronounces the destination as "Nivadellir" instead of "Nidavellir". He says it wrong twice in that scene. Yet, In the third act of the film he correctly pronounces it as "Nidavellir".

(at around 31 mins) Peter Quill/Star-Lord tells Thor that Thanos is Gamora's step father. Thanos is Gamora's adoptive father, he was never married to Gamora's mother.

Upon Reaching Earth, Banner informs Tony (and Dr. Strange) about Thanos. But he never met him in his normal state but only as HULK. He is not suppose to remember the events taking place after he has turned into Hulk.

Post credits: In Captain Marvel, Nick Fury says everyone refers to him only as "Fury", but prior to the crash Agent Hill screams "Nick".