Room 13 is rumored to be haunted by Captain Dearduff the Hooker, a supposed serial killer from 1843 who froze to death because his hook was stuck on the wall.
Unaware of Barney's plan, Robin mentions that the release of the doves would be problematic as her family will do a 21-gun salute with real bullets when they leave the church.
He manages to soothe Lily back to sleep by singing Marvin's lullaby, but his search is interrupted by Barney, who is in the air ducts leading to the room, just like the 'bad guy in Die Hard'.
When Robin appears from under the food service cart, she reveals that Marshall also called her to delete the text on Lily's phone with a "No questions asked" she owed him when he helped her escape from a mysterious group who knew her as "Nightfalcon".
However, they are stunned when Ted interrupts their plan and learns that he has already deleted the text by getting Lily to destroy her phone using a "No questions asked" she owed him when she had been tied up by her kindergarten class.
[1] Max Nicholson of IGN gave the episode a 7.7/10 rating saying it "was a solid effort in weaving together a clever Halloween-esque story, especially considering the time-constricted circumstances.