Shout Out / Spriggan

The entire series:

• Major Fatman and Little Boy are named after the two nuclear bombs dropped on Japan.
• ARCAM could be possibly an allusion to Arkham. According to this article, it's potentially possible that the creators of Spriggan made the spelling intentional, while having some Lovecraft inspiration.

Manga-only:

• One of the signboard in the First Mission oneshot has a Principality of Zeon sign on it. It's hard to see unless you take a good look at said page.
• The way the YAMA virus makes threats to send the world into a nuclear war is similar to what Skynet would do. The computer it infects also bears some resemblance to HAL
• Rick Bordeau's first introduction in Romania to Jean can be seen as a homage to the Star Wars franchise. Ryoji Minagawa is an avid Star Wars fan, having watched it because it was made by George Lucas.
• Jack the Ripper, a Trident mercenary operative with Orihalcum blades in his arms takes his codename from the British serial killer of the same name.

Anime-only:

• In "The Forest of No Return" episode, Yoshino shouts if they're in a Night of the Living Dead situation after she and Yu meet Akatsuki for the first time.