According to the Arthurian legend, Excalibur was not the sword in the stone. Excalibur was given to Arthur by the Lady of the Lake.
During the fight with the Lost Boys, Hook threatens Felix, reminding him of what he did to 'Rufio' a character not featured in this show. Rufio was leader of the Lost Boys in the film 'Hook' (1991), which starred Robin Williams as an adult Peter Pan. Rufio was killed by the hand of Captain Hook (Dustin Hoffman) near the end of the film.
The first time the sword, Excalibur is ever mentioned or used in the show. Second time any item or person is referenced to Camelot.
Emma calls herself the leader and later the gang follow her to find Henry: a nod to the song "Following the Leader" from Peter Pan (1953).