Andrea Arnold had the idea to let Kathryn and Griffin be what can only be described as an entwined marital sea creature on the sofa. Her original cut of the scene was 13 minutes of these two brilliant actors riffing on monogamy.
Griffin can actually throw up on cue. Without using his finger.
The letter Devon reads to Toby is taken from Chris Kraus' description of a performance piece called, route 126, by Judy Chicago.
The inspiration for this episode came from a scene in the book, where Chris accidentally sends Dick a love fax to his university office. The two try to stop him, or any of his colleagues from seeing it. The writers stated that it had sort of a Marx-brother-y feeling.
The first Marx-brother-y idea was to have Chris mail the letters, then try to break into the mailbox. This would be followed by the two driving all over West Texas chasing the mail lady to get them back, buddy comedy style. At one point, Sylvere would have lied to a postal worker that Chris had a medieval disease called Puerperal fever that had caused all the water from her uterus to leak up to her brain and in a fit of madness, she had sent a suicide note to her mother that they had to retrieve. The version seen was chosen over this one.