Inside the suits, a series of spring-loaded clips held back the heavy mechanical skeletons (the endoskeletons). When tightened, a performer could climb inside.

These springs were notoriously fickle. Any moisture—even a drop of sweat or a deep breath—could cause the locks to snap shut, instantly releasing the machinery into the space occupied by the person inside. The Night Shift Routine

As the clock ticked toward 3:00 AM, the silence was broken by the rhythmic clack-clack-clack of servos. The animatronics weren't just statues; they were programmed with an early form of "free-roaming" mode to prevent their servos from locking up due to inactivity.