The Egg Corridor Detour is a location used in place of the bridge leading up to the Side Room and Egg No. 00 in Egg Corridor?, due to the bridge collapsing. This area consists of Critters, Beetles, Basu, and the Time Bomb in small increments. It seems to have a focus on hardly-used features in the original Cave Story and also adding features that would only be possible for a 3DS version of Cave Story, with the transporter tubes being an example.
The Falling Tower is discovered during the escape sequence after defeating the Undead Core. The area seems to have a heavy focus on the Ravil, with Presses used later on. It features multiple pathways which branch and reconnect, depending on how far in the player is. Despite the name, it doesn't use the falling blocks present in most other areas that are crumbling.