Whoever gathered the footage for the documentary should have paid attention to the source they got it from. This should have told them it wasn't an official game, so they would have known to skip it and find more fitting footage. Not knowing what "ROM hack" means is hardly an excuse when it takes less than 5 minutes to learn with google. And even if the video's uploader didn't specifically call it a hack, googling "sonic next level" should have told them whether it was official or not. Alternatively, they could have checked something like Wikipedia or GameFAQs to see if it was listed. Really, the fact they didn't even do minimal research to verify the content before using it is their fault alone. It's not the 90's anymore, this kind of info is readily available for everyone with internet access. You don't need to be an "expert on the subject".