Trivia: In the beginning of the film, young Sonic gives Longclaw a flower with spiky petals. This flower is actually based on a flower sprite from the original "Sonic the Hedgehog" video-game for the Sega Genesis. (00:02:16)
Trivia: The dance sequence that Dr Robotnik performs whilst analysing one of Sonic's quills was improvised by Jim Carrey.
Trivia: The music during the opening logos are a variant of the theme from Green Hill Zone from the first Sonic the Hedgehog game from 1991. Additionally, in the opening scene of the movie when Eggman is chasing Sonic, a dramatic version of the theme also plays. Green Hills is also the name of the town most the movie takes place in. (00:00:05 - 00:00:50)
Trivia: When Dr. Robotnik is picking out a song for the dance scene, you can briefly see the band "Crush 40" listed among the artists and playlists on his holographic projection. Crush 40 did music for the "Sonic the Hedgehog" video game series.
Trivia: During the bar scene, Sonic grabs some chili dogs out of the air and quickly wolfs them down. This is a reference to the overall "Sonic" franchise, in which his character absolutely loves chili dogs. (A fact that was first established in the cartoon "The Adventures of Sonic the Hedgehog," and was later incorporated in other media and even the video-game series).
Trivia: The headband Sonic wears while practicing with his nunchucks features the emblem from the title screen for the original "Sonic the Hedgehog" video-game.
Trivia: Sonic's map of the different worlds he can go to with his rings includes a few hidden easter-eggs. In the bottom corner of the map is a picture of a "Chaos Emerald" from the video-games. There is also a world with a checkerboard pattern, which is a reference to the bonus stage from "Sonic the Hedgehog 3."
Trivia: In Sonic's cave, he has repurposed a street-sign into a ping-pong table. If you look closely, the sign reads "Hill Top Rd. Next Exit." This is a reference to the level "Hill Top Zone" from the video game "Sonic the Hedgehog 2." (00:07:07)
Answer: First, it seems Sonic doesn't shed his quills that easily. Tom found one just by sheer luck. Second, yes that ring is likely going to play a part in the sequel.