Joe mentioned that Wally gave him and Cecile a bassinet that belonged to Moses. This is a reference to his time travelling adventures with the Legends, that were seen in the third season of DC's Legends of Tomorrow.
The episodes title is similar to the earlier season 4 episode Therefore I Am (2017) Similar to that episode, this episode features flashbacks of the DeVoes.
Accelerated Man returns, after making a brief appearance in S3, Attack On Central City (2017).
Discovering his intention to use satellites, Cisco likens DeVoe to a James Bond villain.
Cisco describes everything in Devoes wake as the "Home Alone movies", referencing the Home Alone francise which starred Macaulay Culkin in the first two films.