The stallion heart that Daenerys (Emilia Clarke) has to eat was made of gelatin and solidified marmalade, so it was safe to eat. Nevertheless, Clarke said that it had the foul taste of chlorine and raw pasta, so all the gagging and facial expressions required no acting. While filming the scene, Clarke got so much fake blood all over her body that it made her sticky. One time, between takes, she disappeared because she got stuck to the toilet seat.
The episode title refers to Viserys' death by molten gold poured on his head, after misleadingly being promised a golden crown by Drogo. It also has an alternate meaning: Ned realizes that Cersei's children were not fathered by Robert, based on their blonde hair (or "golden crowns"). Cersei's story in The Kingsroad (2011) that she once bore Robert a black-haired boy (a detail not from the books) was probably added to underscore the fact that Robert's true-born children would have had his black hair rather than the Lannister blond.
Ned's condemnation of the Mountain, including the removal of all his ranks, titles, lands and holdings as well issuing a death sentence, is his fulfillment of a long-standing grudge. The books explain that Ned was always horrified that the Mountain never had to answer for brutally raping and killing the Mad King's innocent daughter-in-law, and murdering her children.
Viserys' death is reminiscent of an actual practice by the Mongols of Genghis Khan, who were known to execute royal or noble enemies by pouring molten gold on their heads or down their throats. The Mongols did this because they had a strict prohibition against shedding the blood of any member of nobility, while Drogo does it because it is forbidden for anyone to draw a blade in the sacred Dothraki city of Vaes Dothrak.
This episode marks the first time that Tyrion attempts to tell a joke that starts with "I once brought a jackass and a honeycomb into a brothel". Over the course of the series, he attempts to tell the joke twice more, but he is always cut off before he can finish it. Most people believe that the full joke is some variation on the following: A dwarf enters a brothel with a jackass and a honeycomb, asking for a lady to lie with since his own wife has left him. The madame asks him: "What's with the jackass and honeycomb?" "My wife and I found a genie in a bottle who granted us three wishes", the dwarf says. "My first was to give her a home fit for a queen, so the genie gave her this honeycomb. My second wish was for her to have the finest ass in the land, so the genie gave her this donkey. My third wish was for my tool to hang down past my knee, so the genie shrunk my legs and turned me into a dwarf!"