Avengers: Age of Ultron

Scarlett Johansson was pregnant during filming, so many of her scenes were scheduled early in filming before she began to show. To help hide her pregnancy later in filming, three stunt doubles were hired. This caused a lot of confusion amongst the other actors since, according to them, all of the stunt women looked very similar to Johansson. Chris Evans stated that it got to the point where he would say hello and start a conversation with one of them only to realize midway that the person he was talking to wasn't Johansson. Ultimately, some scenes used CGI to hide Johansson's belly.

As Sokovia is rising to over 18,000 feet, the temperature would have been dropping about 5.4 degrees (F) per thousand feet. The temperature would have dropped below zero, yet no one's breath is seen and no one is acting cold.

SPOILER: There is a scene in the closing credits: Thanos puts on his Infinity Gauntlet, declaring he'll hunt for the Infinity Stones himself.

Edited into The History of the Hands (2016)