Continuity mistake: In the flashback during Magneto's memorial, when the Nazis are approaching his home it says "Lehnsherr" on the door. After they kick the door open, the writing on the door has disappeared and either a hatch or a small window has appeared on the door from nowhere. (00:06:20)
Audio problem: When Fabian Cortez says "Mark my words X-Man. Before this day is done you will beg me to let you join us," his mouth movement is out of sync with the words "is done." (00:05:40)
Continuity mistake: When Fabian Cortez is scapegoating Gambit in front of the mob, he grabs him by the blue clothing that lines the body armor on his chest. When he says to Gambit "Mark my words X-Man..." the blue clothing is now the same brown color as Gambit's trenchcoat. (00:05:20)
Continuity mistake: When Rogue is asking about Gambit's whereabouts, she along with Beast and Xavier are close to the front of the shuttle. When the shot changes, the three of them as well as one of the astronauts are suddenly further back in the shuttle (note the doorway). (00:04:25)
Factual error: Even though Xavier is a paraplegic, you can see him freely moving his legs when the astronaut helps him out of his seat and walk over to Beast. (00:04:20)
Audio problem: Beast's mouth is wide open when he says "Feet don't fail me now." (00:02:05)
Continuity mistake: When Magneto first notices the missiles being fired at Asteroid M, he is dressed in loungewear and Xavier is wearing his usual green suit. When the shot changes Magneto is suddenly wearing his costume and Xavier is wearing a more casual outfit. Given how fast the missiles are shown to be approaching, they wouldn't have had time to change their clothes. (00:15:45)
Continuity mistake: The missiles that are fired at Asteroid M are first shown to be approaching from Earth. When the shot changes, they are coming from the opposite direction. When the shot changes again, they are once again approaching from Earth. (00:15:45)
Continuity mistake: A crowd of people has suddenly gathered in front of Magneto when Xavier says he wishes to speak with him. (00:14:20)
Audio problem: When Xavier is saying "I fear Magneto may come to depend upon it like a drug," Beast is actually the one mouthing the line. (00:14:15)
Continuity mistake: When Gambit is trying to distract the Sentinels, both of his gloves are entirely fingerless whereas normally his gloves are only fingerless for the thumb, index and pinky fingers. (00:12:00)
Audio problem: Fabian Cortez's mouth is closed when he says "Lord Magneto." (00:10:15)
Continuity mistake: When Magneto is showing Asteroid M to the delegates at the U.N. meeting, the Genoshan delegate he forced to sit down has either moved to another seat entirely or the people that were sitting around him moved to different seats and other people filled in their seats. (00:04:05)
Continuity mistake: When Magneto forces the Genoshan delegate to sit down, the chairs surrounding him are empty. A couple of shots later, the chairs are occupied. (00:02:35)
Continuity mistake: After Magneto crashes through the roof of the U.N. building, the nameplates designating the nations of the delegates have suddenly become blank. (00:02:20)
Audio problem: Magneto's mouth is closed when he says "The mutant race will no longer be managed, mister delegate." (00:02:20)
Continuity mistake: The exit door and stairwell outside of the town hall are shown to be at the very edge of the building when Proteus goes through it. When Xavier, Beast, Rogue and Wolverine use the same door and stairwell, the building suddenly stretches on for several more feet. (00:13:20 - 00:13:55)
Continuity mistake: When Proteus leaves the town hall, the door he exits is shown to lead into an alleyway. Moments later when Moira exits through the same door, it is shown to be leading into a corridor in the same building. (00:13:15)
Continuity mistake: When Xavier is speaking to Proteus telepathically, the position of his shirt and jacket sleeves go from being a few inches below his wrist in one shot, and then just slightly under his wrist in the next. (00:12:55)
Other mistake: Moira's arms are disproportionately long when she rescues Xavier from falling into the pit. (00:12:30)
Answer: It appears a number of factors led to its demise. It was originally intended to air for 65 episodes, but its popularity extended that. However, there were continual production quality problems, issues regarding whether the content was suitable enough for children, as well as financial considerations that finally led to it being ended.
raywest ★