I've liked the show all along, I don't want big name superheros, they simply can't be done properly on a television budget. However, bringing in lesser known characters is perfect. It also shows the kind of training and missions that characters like Agent Romanov and Hawkeye would have gotten their start from. The…

They were never supposed to leave the train, only put a tracking device on the black case with the tech. Once they were all separated, Skye took it upon herself (along with Fitz) to follow the case to the mansion where Quinn was at. It wasn't part of the original mission.