Continuity mistake: During the big battle against the Chitauri, Captain America is zapped with a blaster bolt. When Thor helps him to his feet we can see a significant amount of damage done to his suit, just below the star on the right hand side. But later on after Iron Man destroys the Chitauri ship with the nuke, the damage is completely gone. (01:59:25 - 02:02:40)
Visible crew/equipment: After Doctor Strange experiments with the magical doorway in the Sanctum Sanctorum, he leaves it on a desert view and we cut to a shot panning across all the artifacts. At the very start of the shot on the right hand side of the screen is a crewmember standing in the shadows looking bored. Really blatant if you turn up the brightness, but easy enough to spot if you know what you're looking at. (00:56:00)
Continuity mistake: When Doctor Strange attempts to use the Time Stone on Ebony Maw, Maw ties up Strange telepathically and strangles him unconscious. Beside Strange is a police car and a motorbike tipped on its side. Maw then lifts the ground he is lying on, but the police car has been replaced by an SUV and the motorbike has disappeared. The shadows also change. (00:23:25)
Continuity mistake: After Peter gets the text from Happy about meeting at the bathroom, Michelle asks, "What are you hiding, Peter?" and just as she says, "I'm just kidding I don't care," Peter's holding his cell phone up in his left hand, but next shot he's holding the cell phone up in his right hand.
Continuity mistake: When Sam asks "How do we tell the good guys from the bad guys?" and Steve replies "If they're shooting at you they're bad", Sam unleashes his Falcon wings. This shot shows Steve and Sam to be standing within a few feet of each other, but in the next shot where Sam flies off in his Falcon wings and Steve leaps off the roof, the two are suddenly several meters away from each other. (01:35:35)
Continuity mistake: Vers KOs the Skrull she does the warcry thing at, and then another one on the corridor steps. She is then seen fighting from the perspective of the corridor to her right, but there are no Skrulls in sight against that door, while at least one was already lying down there. There are two when the camera gets back closer, and when she neutralizes the last one who bounces onto his own stun mace, there are again two, and she somehow got between the last one and the others. (00:20:30)
Continuity mistake: When Steve and 2012 Steve fall down to a lower level of the building during their fight, they break a couple of glass barriers and floors, causing loads of shattered glass to surround them when they land. The compass with Peggy's picture is shown on the ground with glass surrounding it. The amount of glass shown around the compass changes between shots. (01:22:50)
Continuity mistake: When Quill and Gamora first meet and get into a fight, Gamora grabs the Orb Quill is carrying and runs. Quill throws a sort of laser-based "lasso device" that snares her legs and causes her to fall. She pulls it off, and immediately in the next shot, it's vanished from the ground between cuts. It also had mechanical components, so even if the laser vanished, the mechanical pieces should still be on the ground.
Continuity mistake: When Cross is seen inside Hank's home, he is wearing black gloves, a few moments later, in the same scene you can see that he is not wearing them anymore.