Though they had divorced by the time she met JFK, Judith Campbell, the historical figure played by Elena Satine, was married to actor William Campbell, a recognizable face to Star Trek (1966) fans as the Q-like being Trelane in "The Squire of Gothos (1967)" and Klingon captain Koloth in "The Trouble with Tribbles (1967)".
The idea of sending a message through time to the future using Western Union was used in both Back to the Future Part II (1989) and Quantum Leap (1989) episode 1x04, "The Leap Back - June 15, 1945 (1991)".
Elena Satine (Judith Campbell) and Abigail Spencer (Lucy Preston) worked together previously on A Beautiful Now (2015).