The title is also the name of the song, "Run Boy Run" by Woodkid, that plays in the beginning when Number 5 time jumps.
Based on the poster for Diego's fight, Reginald died on the night of March 21, 2019.
One of the songs is "Never Tear Us Apart" by Paloma Faith. Faith has known Robert Sheehan (Klaus Hargreaves) for many years.