As part of his costume for The Thing, Michael Chiklis wore prosthetic teeth. To prepare himself to speak with the prostheses, Chiklis wore them when reading to his children.
Stan Lee has said that Michael Chiklis's Thing is his favourite performance in any "Marvel" film ever.
For most of the shoot, Michael Chiklis was terribly uncomfortable in the hot Thing suit. The final street battle, however, was filmed in Vancouver in December, leaving Chiklis as the only comfortable one of the four (the rest were in the skintight blue uniforms).
Jessica Alba had a kidney infection during the filming and nearly fainted when she was with Julian McMahon in the space station scene. Julian calmed Jessica down as he was doing a Dr. Evil impression and joking around.
Ioan Gruffudd's efforts to keep an American accent continually were hampered by the fact he would receive new script pages on a regular basis, forcing him to learn new lines at short notice.
Stan Lee: (at around 43 mins) Although Lee has made cameos in many Marvel movies, this is the first time he has played a character from the comics: Willy Lumpkin, the Fantastic Four's kindly old mailman. His line was supposed to be, "Welcome home, Dr. Richards," but he changed it to, "Welcome back to the Baxter Building, Doctor Richards!"
Ralph Winter: (at around 1h 35 mins) the film's producer, playing the construction worker at the end of the film who closes the container door on Dr. Doom.
Richard Ho: one of Wizard magazine's staff writers, appears as one of the reporters in front of the Baxter Building in a crowd sequence. Wizard is one of the most successful and popular magazines about the comics business.