- Keep Circulating the Tapes: Despite being one of the most iconic arcade shmups, Raiden II has not had a rerelease since 1995 when it was included on The Raiden Project, which is long out of print. However, in 2014, after well over a decade of dealing with encryption issues, the game was finally brought to a working state in the MAME arcade emulator.
- No Export for You: The Playstation port of DX was only released in Japan.
- Sleeper Hit: As revealed in this interview, the original game was a low-expectation project only made because the developer's previous game flopped and a vertical shmup was all they could do with the alloted budget. The game initially sold poorly, but eventually ended up being very successful thanks to positive word-of-mouth.
- Vaporware: Raiden V, a straight-to-console title for Xbox One, was supposed to have a late 2015 release (to coincide with the series' 25th anniversary) after being revealed in Tokyo Game Show in September 2014. However, due to unknown reasons, the development has been subsequently delayed, possibly to have some of its features perfected. It was Saved from Development Hell, and finally had a release date of February 2016, somewhat later than it was expected.