Ezio Auditore de la la la
I thought this was a nice touch. In my view this is clearly a reference to Ezio and the Assassins Creed II Discovery game for Nintendo DS and IoS that released in 2009. Within the storyline of that game, Ezio was actually in the Granada region of Spain at the same time as Aguilar and co in 1491, and even came close to assassinating Torquemada himself.
It is perhaps a sad thought that no true cameo of the great Assassin was made in the movie, given this obvious overlap in game and movie timelines.
UPDATE: In a recent Reddit AMA, Aymar Azaïzia confirmed that Discovery is now no longer considered canon within the franchise. That explains that one then.