In a previous episode, the group showed what happened to the elevator in a flashback scene when Leonard accidentally mixed the wrong measurements to create an explosion, which he set off inside the elevator. In the years since, it has never been fixed, forcing the pals to climb up three flights of stairs to what was formerly Leonard and Sheldon’s apartment.
On a more serious note, Galecki adds that it’s going to be a tough episode to film, and he literally is brought to tears in the interview.
“None of us are going to be able to keep from crying during the last taping,” he says. “We’ve got to justify it in the writing somehow, sensitive group.”