The time between Death of the Speed Force (2020) and Mother (2021) cannot be accessed by the Speed Force because it didn't exist then. However, it can pull speedsters out of that time if it wishes to.
Grant Gustin (Barry Allen) and Candice Patton (Iris West-Allen) had previously expressed interest in having a wedding vow renewal for their characters in because they had discomfort with how the wedding was done and wanted to have a wedding event for their characters in their own series instead of a "shotgun wedding" on DC's Legends of Tomorrow (2016).
This is the second two-parter directed by Chad Lowe, the first being The Last Temptation of Barry Allen, Pt. 1 (2019).
The "Flame On" catchphrase suggestion is used by The Human Torch from The Fantastic Four of Marvel Comics.
When Nora brings Barry, Bashir, Alexa, and Deon into the Speed Force, it takes a swirling orange cloud form; with purple light flashing. Nora (2018) implies that this is actually a damaged state because it normally creates illusions of Earth.