"Legends of Tomorrow" is suffering from not much plot development, and an unclear focus of where it wants to go. In this episode, the "legends" jump ten years into the future with the objective of breaking into the Pentagon and steal some information that will help them stop Savage. Why and how, and all those minor details that make a show have any kind of logic don't matter much.
Nonetheless, the show keeps doing a good job in the way it uses its characters (even if some are underused), and in fleshing them out and making them fun to the viewer, and the pace is fast enough that it doesn't become boring. But those two aspects will wear thin if the show doesn't offer much more in the plot department, as there doesn't seem to be much meaning in these legends' adventures. The show is still on its first steps, though, so it have lots of time to improve.