Continuity mistake: In the final battle, Wasp and Ant-Man are in the van trying to get the quantum tunnel operational. We cut back to the fight and we can see Ant-Man there too, fighting in his giant form. (02:22:20 - 02:23:00)
Continuity mistake: When Karl Urban is defending the Asgardians, the dust covers on his rifles vary between being open and closed several times. M16 dust covers are sprung loaded - they open on the first shot and have to be manually closed afterwards.
Continuity mistake: Cross is holding a normal striker fired (no external hammer) Glock handgun against the head of Ant-Man. In order to save his life, Hope orders the ants to block the firing mechanism of the gun, and they block a suddenly-visible hammer on the Glock. (01:26:00 - 01:27:00)
Continuity mistake: When Klaue is being rescued by Erik, the amount of blood from his face wound changes between shots.
Continuity mistake: As Vers is about to punch the person dressed like the Skrull, a woman in a flowery pantsuit is visible in the background, behind him. Next shot and she is walking behind Vers making a rather conspicuous horrified facepalm, and coming from the wrong direction. (00:33:50)
Continuity mistake: In the final scene when Stark, Rhodes and the senator have a picture taken, Tony's jacket is first buttoned, then unbuttoned from the same viewing angle. (01:56:50)
Continuity mistake: When Pepper is watching the television program about Stark Industries' stock troubles, after Tony's press conference, notice she has a wireless headset in her left ear. When Tony calls her down to the lab, the camera flashes back to Pepper and the ear piece is gone. (00:48:50)
Continuity mistake: Strange is at home, looking for help on a video chat. His friend says no, and in his rage he sweeps almost everything off the table including the Microsoft Surface laptop. Christine enters with food, we cut back, and the area of the table to his left, which was totally clear a second ago, now has several pieces of paper on it and the laptop with a closed lid. A few moments and cuts later, the laptop is in perfect condition on the table with lid open.
Continuity mistake: During the street chase in Brazil, the time of day changes from night, to perhaps late afternoon/evening, to night again.
Continuity mistake: On the spaceship, Peter is talking to Tony, and has his hair swept back with gel or similar. When he says "You can't be a friendly neighbourhood Spider-Man if there's no neighbourhood", we cut to Tony then back, and Peter now has a fringe with no gel. In later shots it's back how it was before.
Continuity mistake: When Peter and MJ hug on Tower Bridge he gets some blood from his face onto the left shoulder of her jacket. From other angles there's no blood.
Continuity mistake: After S.H.I.E.L.D "borrows" Jane's research and Darcy says that they took her iPod, her hair can be seen blowing in the wind in the shots facing her left and not blowing in the shots facing her right.
Continuity mistake: When Spidey first interrupts the criminals on the ferry, there are 2 motorbikes behind him on the left. When he throws one of the bad guys around with a web, the bikes have moved to the right, along with the yellow markings they were on, showing the shot's been flipped. They then move back.
Continuity mistake: SPOILER - The wounds on Pietro's body change. The most noticeable one is on his right shoulder. The amount of blood decreases too.
Continuity mistake: After Tony gets the armor back at the Mandarin's hideout and meets up with Rhodes, they go by boat to the harbor. On the way Tony calls the Vice President - during this scene the VP's phone changes, note the camera on the back of the phone is visible, but in another shot right after, it is a completely flat back panel. (01:30:10)
Continuity mistake: After Steve throws Heinz Kruger, the assassin sent to kill him, out of his boat, both Steve and Heinz are bone dry despite being fully submerged in water only moments before.
Continuity mistake: When the winter soldier is getting away from the police in Bucharest he jumps to the next building and the sun is shining directly onto the ground. When he lands the sun has suddenly shifted and the shadow of the other building is visible. (00:47:11)
Continuity mistake: Throughout the film, Tony Stark's chest ring can be seen glowing through his shirt except for two occasions when it's suddenly off - after Loki escapes from the helicarrier, and when Loki and Tony Stark are talking in Stark tower, even when he's wearing the same shirt. (01:35:30)
Continuity mistake: Nick Fury's black SUV gets hit by several police cars - the driver's airbag deploys and is visible in all shots until the SUV eventually escapes, at which point the airbag has disappeared.
Continuity mistake: During the opening scene with Ego and Quill's mother, they run into the woods behind the Dairy Queen, and mom is wearing boots with fur trim. When they get to where the Ego's plant is in the ground, she is suddenly wearing sandals.
Suggested correction: He needed to hot-wire the van. It's quite possible he could have left the van for parts (he's seen slamming a Leviathan to the ground) or to protect it. It also could have been an illusion by one of Dr. Strange's people.
Sorry but the suggested correction makes no sense. For one Dr Strange's people have no idea what Ant-Man looks like, and secondly Ant-Man would have no idea where to get parts from in the middle of a battlefield, let alone know if alien technology would be compatible. Also the time frame given when the scene plays out allows no time for him to leave the van, this is a legitimate mistake.
Dr. Strange's people don't know what Ant-Man looks like? He entered the battle with them long before they went to the van. Earth has had access to the same Leviathan parts since the original Avengers. If Toomes can make wings out of it in Spider-man Homecoming, it's possible he can figure something out. Clint had passed the glove to Black Panther before Ant-Man is seen in the background. There was plenty of time. He also could have been defending the van while they brought the glove.
There is plenty of time for Ant-Man to have left the van and returned to it. As the scenes play out, Ant-Man and Wasp are in the front of the van trying to hot wire it. The film then cuts to the battle for several minutes, as we see the passing off the gauntlet, which includes the brief shot of Giant-Man in the background. A few minutes later the film cuts back to the van and we see Scott opening the rear door of the van. So there's plenty of time for him to have gotten out of the van, saw potential trouble with the Leviathan, turned into Giant-Man to stop it while letting Hope finish activating the tunnel, and then returning to check the final settings. Now, all this raises another question that has to do with the apparent ease Giant-Man has in traversing the battlefield, as in why not just give Scott the gauntlet, have him turn into Giant-Man, take a few steps over to the van, and then shrink back down to take the stones back in time?