Trivia: Taron Egerton refused to shoot the scene where he implants the tracking device into Charlie's girlfriend's groin, as he felt uncomfortable touching the actress in that area. The hand we see reaching down into the woman's underwear is actually the hand of the actress' husband, who gladly volunteered to "double" for Egerton's hand in that scene.
Trivia: Director and co-writer Matthew Vaughn wrote the script about two years before the film was released. While working on the script with his writing partner, he included the song "Country Road" and several references to the singer John Denver, as he felt it was odd that such a celebrated and known singer as Denver wasn't being referenced much in movies or TV anymore. Evidently Vaughn wasn't the only one who had this same idea, as amusingly and coincidentally, "Kingsman 2" ended up being one of many films released in 2017 that either featured Denver's music, referenced him or featured covers of his songs. (Other notable 2017 films in this group included "Logan Lucky" and "Alien: Covenant.").
Trivia: Spoilers. Originally, Merlin was meant to survive his apparent demise, albeit having lost his legs to the land-mine. He was going to humorously appear asking for a "bit of help" sans legs in a bit of dark humor. This was cut out after test-audiences found the idea that he lived hard-to-swallow.