On the radio, Lyla signals ARGUS using the code name "Harbinger". In the famous DC Comics crossover Crisis on Infinite Earths, Lyla Michaels becomes the Harbinger, working for the Monitor to protect the multi-verse from the Anti-Monitor.
This is the second Suicide Squad themed story in this series.
In season 1 Deadshot had Andrew "Andy" Diggle's name tattooed close to the base of his neck, even taunting John that there was space for his name next to his brother's while showing him the tattoo. However in the season 2 episode Suicide Squad, Andy's tattoo was no longer there or among the names visible, presumably because it would have distracted John from their conversation. However in this episode, we see the tattoo again, now on Deadshot's right peck, second name down, which does become a momentary distraction for John.
John Diggle's baby is named after Sara Lance.
Ray's right eye is extremely bloodshot until the last scene with Felicity.