As Justice League Unlimited drew to a close, so did Infinite Crisis. However, the sequel films have introduced a number of elements from the "One Year Later" Time Skip after IC and the New 52.
Batman and Harley Quinn sees the introduction of A.R.G.U.S., a government agency that first appeared in the New 52, into the DCAU.
Justice League vs. The Fatal Five not only sees A.R.G.U.S., but also both Miss Martian (a character introduced as part of "One Year Later") and Jessica Cruz (who was introduced in the aftermath of Forever Evil) as major characters. Additionally, the film sees Wonder Woman now regularly carrying a sword with her ala her New 52, DC Extended Universe, and DC Animated Movie Universe counterparts and much like in The Dark Knight Trilogy and Batman: Arkham Series, Batman's cape doubles as a glider itself rather than a glider being a separate piece of equipment (though admittedly, that one could also serve as a Call-Forward to the Beyond Batsuit and Batman not taking any chances after he had to eject from the Batwing during "Dark Heart" and call for help).
After being uncancelled in 2019 (having been cancelled in 2013), Young Justice introduced some elements that were going on in the comics since its cancellation, including Harper Row (best known as Bluebird in the comics, introduced in late 2011/early 2012 but didn't become Bluebird until 2014) and Jonathan Samuel Kent (introduced in 2015).
If I understand the trope correctly, these aren't backported developments, they're just developments. If Fatal Five or Young Justice: Outsiders had flashbacks claiming Jess, M'gann, Harper, or Jon had always been there, that would be a backported development.
I pulled these from the Western Animation:
If I understand the trope correctly, these aren't backported developments, they're just developments. If Fatal Five or Young Justice: Outsiders had flashbacks claiming Jess, M'gann, Harper, or Jon had always been there, that would be a backported development.