At the beginning of The Black Knight both Gawain and Percival show signs of being torn between their duty and sense of right and wrong. This makes perfect sense for these two characters, considering that they're this game's versions of Knuckles and Blaze, respectively, and both are Guardians saddled with important duties. Interestingly, Gawain is the first to question what the knights have been instructed to do. On a side note, he also tried to commit suicide after failing in his duty (losing a fight to Sonic). Coincidentally, the same thing happened in the main series, minus the sword fighting. We can assume that, even if seppuku-like tendencies aren't unique to the Arthurian universe, it didn't go anywhere in the main one... but it's still an unnerving thought.
One thing about Sonic and the Secret Rings that kind of bugged me is why Erazor Djinn needed to sacrifice the collector of the seven World Rings, in this case Sonic, in order to access their power. Then I remembered that the characters in the story couldn't touch the rings, only Sonic could. That leads me to think that Sonic could use the power of the rings without the sacrifice, as he could touch them to begin with! It would also help explain why Sonic was able to draw some of the World Rings away from Erazor is because Sharha was killed instead of Sonic. She helped him on his quest, but wasn't directly responsible for collecting them. Thus, Erazor's control of the World Rings was incomplete and Sonic's negative emotions let him take those specific World Rings away. - Drakohahn
In Sonic and the Secret Rings, it's heavily implied that Erazor and Shahra were once together at one point, but it's never truly stated what it was they were before exactly. Shahra is very resistant to his influence until right before the final battle where she (rather easily) gives in to Erazor while the other times she was still firmly against him. I believe that Erazor was using some sort of ambiguous Mind Control at the last minute to control Shahra into giving him the World Rings. When Shahra speaks, her tone is very monotonous as if she's not showing emotion at all. Why else would Sonic's wish cause her pain when he wished for her to "do what was right?" Also a minor eye-catcher to add to this theory is that once Sonic makes the wish, Erazor's lamp immediately appears right behind Sonic and Shahra, and yet it never shows that Shahra intentionally left this behind. - Mysterious Mr X
In the Black Knight Universe Sir Lancelot is right handed unlike Shadow who is left handed, this makes sense since during Medieval Times left handed people couldn't become knights since they were thought to be demons.
In the main continuity, Shadow is made from Black Doom, who is a pretty demonic individual with a final form called "Devil Doom." Maybe Lancelot is trying to hide something...?
It seemed kinda like an Ass Pull that there just happened to be the barrier stones needed to stop Merlina's magic until you realized Merlin and Merlina both have knowledge of future events and Merlin put them there because he knew Merlina would be corrupted.