At one point, Ed, Al, and Ling end up in a battle involving Gluttony. Then,
Ed, Ling, and Envy are swallowed by Gluttony, which lands them in another dimension.
It is also stated more than once that alchemists use the energy from the movement of the tectonic plates of the Earth's crust (though this is not entirely accurate, the inaccuracy is irrelevant for the purpose of this question). This energy would not be present on another planet, much less in another dimension.
In order to escape from this alternate dimension, Ed performs human transmutation. He uses Envy's philosopher's stone to do so, meaning that he would not require this energy. However, prior to finding Envy, Ed uses alchemy to fashion a cooking pot (evidenced by the transmutation marks on the pot). He also uses it to turn the iron from the blood into a weapon.
This should not be possible; there should be no energy for the use of alchemy in that dimension. Is this an oversight by the writer(s), or is there some explanation?