Tangled. Rapunzel magic hair works instantly after the wound is bandaged with It and the hair glow as rapunzel sings
the emperor's new groove: Except for the potion that turned kuzco into a llama at the beginning of the film, all of yzma's transformation potion work inmediatly
iron man 2. Tony stark is dying of paladium poisoning from the arc reactor that powers his heart. Yet when he invents a new arc reactor that doesn't use palladium and plugs it into his chest, the visible symptoms recede immediately
also he receive an injection developed by SHIELD specifically for this case, which temporarily reverse the toxic effects.