Wolverine cannot be duped easily by shapeshifters with their disguises like Morph and Mystique as he can easily identify them just by smelling them.
Wolverine... I felt him... such pain.
Gambit: Man been a pain since the get-go, Chère.
In the opening theme scene, the X-Men charge against the Brotherhood of Mutants. One of the team members on the Brotherhood is an man dressed as an Indian. That Indian character is named Thunderbird and, according to the original comics, is a hero of the X-Men.
At the beginning of the opening credits (Season 1-4), the X-Men first soar through space and through the series title. At the end, the X-Men and the Brotherhood of Mutants collide with each other and form the series title.
Mr. Sinister's original voiceover at the end of the initial airings of "Final Decision" was replaced when the character was cast for season 2.