The first time that the Voltron Force are actually shown entering a circular room with their usual garments after riding rails down, showing that they likely enter the five doors within to don uniforms and again travel on similar devices to the Lions.
The first time the shots of the Voltron Force entering the elevators wasn't in numerical order (Pidge was shown entering 3 after Lance and Allura had entered 2 and 4. Also, when they entered the chamber as a group just before being transported to the Lions, Keith arrived a moment after everyone else so must have boarded 1 last.)