The movies are so epic that you are just focused on not missing one moment. Typically one would have to re-watch movies multiple times to catch things that they didn't recognize the first time. So many things are happening in Marvel movies that it can seem like an overload. That being said check out some of the errors you might have missed the first times watching!
• Black Panther and his special silent shoes not being very silent.
• Which version of Earth were Ego and Star-Lord’s mom on in GOTG Vol. 2? Not to mention her magically transforming shoes.
• More magically appearing objects in Thor: Ragnarok.
• Vulture drinking beer in a bottle that hadn’t been produced yet in Homecoming.
• Thor being on the completely wrong London train in Dark World.
• Black Widow’s killer hair.