None. Some characters are implied to have a boyfriend/girlfriend relationship, and one character is married with a child, however the show contains no sexual/mature content whatsoever.

Fantasy violence - missiles, ray guns, and the like. Occasionally characters die, but these are usually just "redshirts" who we do not get to know or overly sympathize with. Most characters who die are evil anyway. The show is no more violent than a Saturday morning cartoon, and it is rather obvious that the "characters" are just puppets anyway.

None. Characters occasionally insult and heckle each other, but never with any profane language.

Characters are shown drinking/smoking from time to time, however no one ever gets high or drunk. The activities are just done socially, and are not glamorized.

Our heroes regularly find themselves in peril, and often at the mercy of some scary looking, evil aliens. However modern kids are likely to think it all looks "fake" and won't believe that there is any real sense of danger/