The CW's superhero series The Flash depicts the adventures of Barry Allen, "the Fastest Man Alive," as he faces many other superhumans who also received superpowers from a particle accelerator failure. Most, but not all, of his fellow superhumans (called metahumans in the series) to appear so far have been supervillains. One who has been non-villainous, though still dangerous for the destructive nature of his powers and his difficulty controlling them, is Firestorm the Nuclear Man.
The character Ronnie Raymond (played by actor Robbie Amell) is the lead structural engineer for S.T.A.R. Labs' particle accelerator. When the accelerator explodes, Ronnie vanishes. A year later, the show's characters discover that he and another man, Dr. Martin Stein, now share the same body. This merged man looks like Ronnie Raymond, but the person doing the thinking is mostly Martin Stein. Ronnie's memories and motivations intrude upon Stein's enough to create chaos in Stein's consciousness.
In the program's 16th episode, the main characters attempt to separate Raymond/Stein back into being two separate people. After coming to S.T.A.R. Labs, he awakens with a clearer head. "It is remarkable," Stein says with Raymond's mouth, "I feel clearer than I have since the accident." Dr. Harrison Wells explains that they gave him a "cocktail of antipsychotics, depressants, mood stabilizers." Stein, learned man that he is, recognizes this as "the same formula they use to treat dissociative identity disorder," the modern term for multiple personality disorder (MPD). No, it's not.
Because the series is science fiction, medical practice in their world may be different from ours, to be sure. However, that fictional world is presented as being essentially the same as the real world prior to the recent emergence of metahumans there. Their people are still just that—people. When characters are supposed to be every bit as human as those in the real world, their psychological processes should work the same way. Furthermore, most viewers hearing characters casually toss this description about will not chalk it up to science fiction. If they know nothing about DID treatment, they will get the wrong idea and could think it really is "the same formula they use to treat" the condition. If they do know something about DID treatment, they will know this is wrong, and if they're among the many skeptics who question the mere existence of DID, they'll roll their eyes at the whole thing.