Mallory Jansen and Joshua Sasse had three weeks to learn to tango for the song "I Love You (As Much As Someone Like Me Could Love Anyone)."
When King Richard is on his spiritual journey, Xanax says "Petrificus totalus", which is a spell from the Harry Potter series.
Dan Fogelman didn't send Alan Menken's demo for "A Day in Richard's Life" to Ricky Gervais in advance, fearing the actor might back out of the show due to the bizarre nature of the mini-rock-opera that his character performed.
Filming of the song "Love is Strange" took an entire day, and the filmmakers had technical issues shooting through the bars in the dungeon.