Killian would have had to say (after entering the dead-end room):
"Hey, - that gobbo might be hidin' in here, cause I can't see any way outta here.
Little help, lads?"
And he'll look for an open pathway, or footprints that lead into a wall.
If he doesn't quickly see a likely passageway that the wall open into, he'll assume the goblin is hiding in a barrel or keg.