Location mentioned a couple of times by 
Lord Fear during 
spyglass scenes. The first was in 
Series 5, when 
Sylvester Hands was 
slow to respond to his call, and Fear growled "
Drat the rat - I'll have him thrown in the snake pit if he ignores me!" The second was in 
Series 6, when 
Greystagg was apparently concerned about 
Team 6 having come into possession of the 
Hand of Atrab. Lord Fear assured her that he'd sent 
Skarkill and his 
goblins "
beyond the great snake pit and through the Mines of Malapith", so they were sure to catch the 
dungeoneer.
As the snake pit was never seen, it's not clear whether it was meant as a tribute to 
Raiders Of The Lost Ark, or simply the lair of the dreaded Khah as seen in 
Series 3. [See: 
giant reptile]