The missing player created a logical paradox that caused he became simultaneously standing both on and off the platform. This in turn caused a memory allocation bubble to form in the upper portion of unused address space, and filled it with his character data. But the space used by the allocation error probably wasn't very big (they rarely are), and your character data overfilled, resulting in a buffer overflow. This leaked over into the CPU data registers and caused it to overwrite another memory block by mistake, making another write operation hit an access error, and forcing it to find another memory block to write to. Since during a player disconnect, the lack of data flow on the character prop creates a small gap in memory space, and if you take into consideration that the JRE heap size (which is the boundary for how much memory java can actually use) is limited to 256MB, and most of it is probably fragmented, it'll start with the largest contiguous set of blocks it can find and start writing from that address onward. So the overflow from the access error is moved into the block of space that used to contain the data stream for the other player, hits the last open block in the string, and has to put the rest into another open block. The problem is that it tracks this using an address offset from the starting point, but what it doesn't realize is the data start point is where the allocation bubble started... instead it calculates the offset using the original memory address and adds it to the address tables for the data set. The next time the data set is read, the incorrect offset leads the program into reading the memory space used by another chunk of data, and just happen to be the space for your character since they tend to be next to each other. Since it now thinks both of you are standing on the elevator, it starts the script for the end level rewards and the elevator menu.

But seriously.... its probably a glitch unless theres a way to recreate it.