There has been some major changes to the next 2 upcoming episodes of How I Met Your Mother, episodes 19 and 20.
Episode 20 was previously “The Fortress of Barnitude”, it has now been re-titled to “The Fortress” and has become episode 19 airing March 18th.
Episode 19 “The Time Travelers” will now be episode 20 and will air Monday, March 25.
Source: FoxFastTV