Revealing mistake: In the shot where the Falcon is underneath the Star Destroyer, it is transparent and you can see the part of the Star Destroyer through it.
Revealing mistake: In the final scene, Superman is returning the White House's flag to its rightful place, flying over the fountain on the lawn...which is frozen solid in place. Obviously a photo backdrop.
Revealing mistake: When Tony is having his first fight in the embassy, it is obvious that most of his punches do not connect at all. The people he supposedly hit still react as though being hit, and the sound effects of a fist hitting a jaw are still there, even if Tony misses by several inches.
Revealing mistake: When Richard first wakes up after travelling through time, he's supposed to be lying on a couch. Yet there is a wall behind him. It's blatantly obvious that it's the same shot from the modern bedroom, and all they did was change the lighting. (00:33:45)
Revealing mistake: The door to the weather observatory shows that it is a set by the lack of a complete door frame at the bottom which would let rain and other elements in under it.
Revealing mistake: When Hawk is enchanting his fathers sword he holds the "mind stone" in the palm of his hand and you can see a wire attached to each side of the stone. A few seconds later and, of course, it "magically" lifts from his hand. (00:03:14)
Revealing mistake: After the shot that shows Herbie spitting sea water from his exhausts, look at the bumper in the next shot of Herbie, when he gets black smoke from his exhausts. The rust doesn't look real, because they used paint to make it look like rust.