Iris' blog post "The Fire within Central City...and Us All" is dated March 13, 2018, the day that this episode aired.
Jaco Birch may be named after J.J. Birch a pseudonym of DC comic book artist Joe Brozowski who worked for a long time on comics about a fire-related character, Firestorm.
When Harry and Cisco were talking about how to defeat DeVoe they said "We alter each bus meta's DNA by performing intercellular surgery.And what? And turn them into chickens?" A similar thing had happened on Red Dwarf, where a old spacecraft had changed Lister into a chicken.
Max Adler (Jaco Birch) and Grant Gustin (Barry Allen/The Flash) both previously appeared on the third season of Glee (2009).
Most fan theories regarding Iris's purple lightning point to Iris's relationship with the Speed Force, since this is the most obvious difference between her and Barry. The exact science behind the difference was never explored fully in The Flash, largely because Iris opted to not continue having meta-human powers by the end of the episode. Narratively speaking, however, Iris's distinct purple lightning was conscious choice: it was done to hint at the identity of the "mystery girl" seen earlier in the season.