There was originally a character in the game called Tiara Boobowski, but due to the game being cancelled she didn't make her debut.
Contributed by WoopeTon33
There is a fan recreation of Sonic X-Treme under the name Project AXSX. It is planned to be a complete recreation of Sonic X-Treme, and runs on the fan made Sonic GDK engine.
Contributed by PoisonTardis
Due to the stress involved with the game's production, Director Chris Senn actually grew physically ill, stating that he "took on far more than was healthy... and after 2 years I became extremely ill... a nurse told me he thought I had 6 months to live, actually. I lost 25 pounds, was sick all the time, had cramps... and still went in to work... all due to too much stress."
Contributed by SomewhatMystia
The version of Sonic X-Treme we saw in advertisements was scrapped early in development. The slow and unsatisfactory progress in porting the PC engine code to the Sega Saturn caused arguments, and resulted in the executives intervening and bringing in a third party company, POV, to take over programming duties. From then on, three parties worked on the programming separately: one on the boss stages and two on the main game. On the original programmers' side, good progress was made. But POV had no such luck. Due to a poor presentation made by POV, the President of Sega Japan had already angrily left the building when the team of original main-game programmers arrived. In reaction to the poor presentation, the president demanded that the rest of the game be made like the boss engine, which caused further complications and ultimately the cancellation of the game.
Contributed by TheUpbringer