Secret Wars, Chapter 3: Doom - S5-E11
Revealing mistake: After Dr. Doom has stolen the Beyonder's powers, he demonstrates the powers to Ben Grimm in his throne room by teleporting Red Skull, Dr. Octopus and Smythe off the planet. Next he teleports all the heroes to his throne room, and the shot of all the heroes is from two episodes prior when all the heroes were battling the Lizard. This shot of the heroes also includes Ben Grimm in form as the Thing, meaning Ben Grimm was in two places at once. Spider-Man, the Lizard and the rest of the Fantastic 4 were also already prisoners in Doom's castle, which means they were all in two places at once as well.