The Compact trilogy is the only place where the first opening song to Mobile Suit Zeta Gundam, "Zeta - Toki wo Koete", is ever used in the Super Robot Wars franchise, coming not long before the ambiguous legal issues that make the song extremely rare to find in 21st century Gundam games.
Earth Crisis retained the Super Robot Wars Compact rendition of "Silent Voice" from Mobile Suit Gundam ZZ as the series' Leitmotif, but it's never heard in-game as there are no Gundam ZZ characters playable in Earth Crisis. Cosmoquake would opt to replace it with a rendition of "Anime Ja Nai", which carries over into Galaxy Showdown.