In Winter Is Coming (2011), Ned Stark told his sons that the man who passes the sentence should swing the sword. All three Starks who followed that rule so far - Ned, Robb and Jon - were killed in the same season they performed the execution: Ned (executed Will) - season 1; Robb (executed Rickard Karstark) - season 3; Jon (executed Janos Slynt) - season 5.
HBO initially ran into difficulties shooting Cersei's walk of penance because Dubrovnik's Catholic Church of St. Nicholas, which stands in for the Great Sept of Baelor, refused to allow filming of nudity on their grounds. They relented for the nude walk through the streets of Dubrovnik as long as it would not cross onto holy ground, so the crew eventually built facades of the interior and exterior of the church for the scene.
As preparation for filming the final scene where Jon is betrayed and assassinated by the officers of the Night's Watch, episode director David Nutter had the actors playing the mutineers recite the Night's Watch vows together, off-camera. He did this because he wanted the actors to understand that they were killing Jon because they truly believed that he had betrayed the Watch. He wanted their performances to reflect the solemnity of men who believed they were doing their duty, even if it meant murdering their commanding officer.
When Daenerys is stranded in the Dothraki Sea with Drogon, it can be seen that she is wearing riding leggings. While some television viewers called into question the probability that Daenerys would have been wearing riding leggings while attending the opening of the fighting pits in the preceding episode, Michele Clapton, the costume designer of the series, explained Daenerys always wears riding leggings under her gowns out of habit, because throughout her life she had to be prepared to escape at any moment from assassins sent to kill her.
The face Arya wears while pretending to be a prostituted child in order to ambush and murder Meryn Trant, belonged to Ghita, the terminally ill girl who came to the House of Black and White to be euthanized earlier in the season in Unbowed, Unbent, Unbroken (2015).