Devoe telepathically making Joe put his handgun to his head but Joe being able to resist is similar to the episodes Grodd Lives (2015) and Attack on Central City (2017) in which Gorilla Grodd made him do the same thing.
When Barry builds up speed to use sonic punch as an attempt to destroy the last satellite, Marlize stated the action could kill Barry. Interestingly, his action and surroundings are reversed at the last minute before Barry reaches the satellite. This is heavily implies that the timeline has been altered at the moment before he is joined by another speedster who helped him destroying the satellite.
Cisco notes Harry's condition is similar to Barry when he got out of the Speed Force by noticing some of the words Harry says are similar as Barry's. It is interesting to note, his condition is stated to be enlightened by DeVoe in hologram form. Therefore, this makes Barry is the first one to be in enlightened state although his condition is the effect from the Speed Force.
This is the first time since Don't Run (2017) that DeVoe appears as The Thinker in his original look.