The phrase, 「あーうー」 or "aa-- uu--," uttered in Reimu's route in the extra stage, has also become a popular saying attributed to her (as well as a way to refer to her), and is also mentioned by that same song.
The name Suwako (諏訪子) is modified from Lake Suwa (諏訪湖, pronounced Suwa-ko), the largest lake in Nagano prefecture. The area also features one of the world's largest geysers.
Suwako's family name is probably derived from Moreyashin (洩矢神, the god Moriya), who is said to be the first ancestor of Sanae Moriya(守矢早苗), the real person who inspired Sanae Kochiya. ("Moreya" is an archaic, alternate pronunciation of "Moriya".)
It should be noted that some of the fairies in Mountain of Faith seem to be wearing Suwako's hat.
Suwako is the only character known to have children.
Suwako's strongest spellcard in Hisoutensoku resembles the ultimate attack of Akuma from Street Fighter, the Shun Goku Satsu.
Suwako's Theme "Native Faith" is a homage to "Boss6", the BGM used in the STG released by Taito in 1989, Night Striker (ナイトストライカー).
One of Suwako's Hisoutensoku palettes is a homage to Hina Kagiyama.
The frogs printed on Suwako's dress were taken from Chōjū-giga, the picture scrolls drawn in 12th century.
Suwako's catchphrase inspired the creation of the character Hanyū from the anime series Higurashi no Naku Koro ni. In fact, it's not uncommon to see Hanyū and Suwako in fanworks because of this. It's speculated that Hanyū was given this catchphrase to show the relationship ZUN and Ryukishi07, creator of Higurashi, had as friends. It's also speculated that Higurashi Daybreak, the game based on the anime, is also published by the same company as Touhou, Twilight Frontier.