"Opposite Universe"
Spoiler Alert.
In case anyone is not aware of it, this episode is very obviously a parody of, or rip off of, or homage to, the classic Star Trek episode "Mirror, Mirror".
One thing the script doesn't make clear is whether Henry and/or Charlotte have ever seen "Mirror, Mirror". Obviously the Opposite Universe people can only have seen a very different type of Star Trek show.
The opposite Captain Man and Schwoz might be the most evil villains ever in any Nick series, and are certainly a main exception to Henry Danger villains usually being more comic that evil or frightening. Trying to kill their coworker's little sister for relatively minor reasons is very evil, especially since they might have met the opposite Piper and seen that she is as good as "our" Piper is nasty.
Does anyone else think that the opposite Piper is so good that she is a little bad? When Kid Danger and opposite Captain Man were fighting Kid Danger asked for her help and she said sorry she was a pacifist. Being a pacifist doesn't mean that you always have to announce it to evil persons. Since Kid Danger as fighting to save her it would have been better for her to try to grab opposite Captain Man's ray gun and threaten to blast him if he didn't leave (even if it was a lie and she wouldn't have been willing to blast him).
And when opposite Captain Man pointed his "Ray gun" at her and said he would kill her she just stood there and said "okay". Being a pacifist and unwilling to fight even to defend yourself doesn't mean letting yourself be killed like it was nothing. Acceptable options for a pacifist include screaming for help, begging for mercy, running away, etc., etc. Even if they fail to save your life, they might show the murderer that nobody likes to be murdered and that murder is a big deal, and might make him murder fewer people in the future.
Not trying to escape and survive a murder attempt makes you an accessory to your own murder, and being an accessory to murder is evil. Thus some people might say that opposite Piper was so good she was bad!