When Penelope Garcia logs into her work computer she gets a message that says it has been 1009 days since she last logged in. That is the number of days from when the original series finale And in the End (2020) S15 E 10 (February 19, 2020) aired, and when this episode Sicarius (S16 E2) was uploaded to Paramount+.
Guest stars Zach Gilford and Kiele Sanchez, who play married couple Elias and Bridget Voit, are also married in real life.
Even though the BAU destroyed their plane in "In the End" and had a replacement (mentioned at the end of that same episode), it is due to budget cuts that the famous "wheels up in 10 minutes" quote is not used in this episode.
Penelope finds the pink post-it note that she slipped down the side of her desk in the season 15 finale. It's never revealed to the viewer what she had written on it.
The opening quote, which Tara says is attributed to Oscar Wilde but no-one knows the true source of, first appeared in a psychology book in the 1990s, attributed to Robert Alan Glick, professor of psychiatry at Columbia.
He was writing about Freud and psychoanalysis, and the quote was his summary of the school of thought.