Infinity War - the mistake that isn't

One "mistake" that I've seen pointed out about Avengers: Infinity War is the scene near the end where Captain America seems to stop Thanos's hand. (note, that was in the trailer so it's not a spoiler. Everything from here on contains spoilers.)

The "problem" is that Thanos already punched out the Hulk. In fact, he beat the Hulk so bad that he refused to come out for the rest of the movie. There's no way that Cap is as strong as the Hulk so what gives?

The answer has two parts.

First, Cap has super strength in the MCU. We've seen lots of examples of it starting with him running down the Nazi spy in Captain America: First Avenger. In The Avengers he holds his own against Loki. He beats several armored aliens with nothing but a shield. By Captain America: The Winter Soldier he's jumping out of airplanes without a parachute and running rings around Sam. In Captain America: Civil War he holds back a helicopter with his bare hands then he and Bucky (who has been similarly enhanced) beat Iron Man. Clearly Cap is superhuman. He may not be as strong as Iron Man but he's able to do things that would cripple a strong man.

The second part is Thanos. We actually have no idea how strong he is naturally. He already has the power gem before Infinity War begins. The Hulk blindsides him, overpowering Thanos but then Thanos draws on the power gem and beats the Hulk up. This is consistent with the comic books where Drax and Thor were able to increase their already considerable strength by drawing on the power gem.

All during the movie we see that Thanos only uses the gems consciously. That's probably the main function of the Infinity Gauntlet - to insulate Thanos from the stones and let him exert conscious control over them. Ronan did the same thing with the power gem in Guardians of the Galaxy The gem might have been able to destroy a planet but he only used a tiny fraction of its power.

We also saw this during the battle between Thanos, Iron Man, Spider-Man, etc. They nearly overpowered Thanos and got the gauntlet. They could never have done that it he was drawing power from the gauntlet. They managed to keep him off-balance enough that he was depending on his own considerable strength rather than the gauntlet.

This also explains why the effects of the reality gem were only temporary. He wasn't actually changing reality, he was overlaying it with a different one. When he stopped, the original reality returned. The people he sliced into pieces were back together, Star Lord's gun shot energy blasts instead of bubbles, etc.

So, Cap, who has super strength, was able to hold off Thanos who was not drawing power from his gauntlet - but only for a moment.

All of this changed during the battle when Thanos had a vision of Gamora as a child. That's when he finally integrated the gems into a single force and evaporated half of everyone, everywhere.