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: In New York after Bruce tries to become Hulk, in one shot there's a minor mud stain on his shirt, then the angle changes and it's suddenly a massive brown splat. (00:22:15)
Continuity mistake: Thanos' ship is near the ground in New York but seconds later when Peter senses it, the ship is higher, at building level. (00:18:10)
Suggested correction: The two events aren't happening in real time. It's clear Peter sees the ship before it gets close to the ground.
Continuity mistake: In the flashback to Gamora's planet while Thanos is walking beside Gamora, Ebony Maw disappears in the open view. (00:43:20)
Factual error: Peter sneaks off the bus using the emergency exit window, which would have triggered an alarm when he released the red safety latch, ruining his stealthy escape.
Continuity mistake: The blanket used by Thor on the Guardians' ship moves several times between shots. (00:32:55)
Continuity mistake: When Heimdall is stabbed the sword gets into his chest around his heart, in the next scene they take the sword away from closer to his stomach.
Continuity mistake: When Thanos hits Wanda he is grabbing Vision by the neck, but in the next shot he grabs him again.
Continuity mistake: When Ebony Maw walks past the dead Asgardians, Corvus Glaive walks past him with his spear upright then the other way up. The spikes on the spear change shape too.
Continuity mistake: While Tony and Peter talk in Thanos' ship, Peter's hair changes between shots.
Continuity mistake: Before Heimdall sends Hulk to earth he moves his hand between shots.
Continuity mistake: When casting Thor's axe, the forge is barely tilted when the molten metal begins to pour, indicating it was almost full of material. But, in the previous shots, it is not, even after the bars melt.
Continuity mistake: In the close up shots of Thor when Thanos has his hand on him there is blood coming out of his mouth. In the long shots though there is no blood. (00:02:54 - 00:04:04)
Continuity mistake: Thanos reaches down and picks up Thor by the collar of his uniform. Thor is facing head first with his back parallel to the floor. Thanos lifts him and walks towards Loki. In the next shot of Thor he is now sitting upright and Thanos has his hand on top of his head. (00:02:22 - 00:02:54)
Continuity mistake: While Iron Man talks with Thanos on Titan, Tony's facial hair changes color and amount.
Continuity mistake: Thanos stabs Heimdall in the chest but the spear is taken out from his stomach.
