I guess this would be more Hilarious in Hindsight but imagine what the guards posted outside of Arthur's room would have heard in Season 2's episode The Sins of the Father
Arthur: (muffled) What are you doing...the rope!
Merlin: (panicking) THERE IS NO MORE ROPE!
Arthur: (straining): Merlin...
Arthur: (even more strained) ...don't let go of the rope!
(Merlin groans until there's a startled shout and then a thump)
- Merlin had sneaked a length of rope into Arthur's room to help him escape and seek out Morgause. Unfortunately it wasn't long enough to get Arthur down the entire way and Merlin was forced to drop Arthur halfway down.