Came across a videos talking about S-4 near Groom Lake. Apparently the entire second floor is known as "Alice's Floor", and there is a 3ft tall Alice in Wonderland rabbit near the entrance. I have attached some of the images shown in that video. Here is the video I watched. The part about 4-2 starts just after the 25 minute mark. https://www.youtube.com/watch?v=ad3Bb2_vSp8&t=1760s