Tim and Xandir, Sitting in a Tree... - S2-E11
Continuity mistake: In 'Xandir and Tim, Sitting in a Tree', "Tim" gives Xandir a gun to shoot Captain Hero - it is a cartoon version of something like a .38 revolver. Xandir leaves the room and attacks Captain Hero/Tim with an automatic, something like a Colt .45. Completely different guns.
Tim and Xandir, Sitting in a Tree... - S2-E11
Continuity mistake: When an Entertainment Weekly magazine falls onto the table and Foxxy and Clara both hold it. If you look at Foxxy's hand you see that her furry bracelets suddenly disappear and then reappear.
Answer: You might think it has something to do with licensing rights for the characters. But that's doubtful as several of the characters, both seen and unseen, are from the same animation company, Hanna-Barbera. Actually, it's a play on the real-life reality TV show convention of blurring/obstructing the faces of people who haven't legally consented to having their image shown, because their appearance on camera would put them in a compromising position. This happens often in shows like "The Real World, " "Cheaters, " and "COPS." In "Drawn Together, " Snagglepuss and Elmer Fudd, for example, were jokingly portrayed as not giving consent to their image on TV because it would out them as gay in the context of that episode. Of course, to the viewer, it's obvious who they are, and the humor lies in our memory of them as possessing a lot of stereotypically "gay" characteristics. Charlie Brown's face was obstructed by a leather BDSM mask, part of his "costume, " in a scene where Foxxy was his dominatrix. In the same scene, Natasha Fatale has Captain Hero in a similarly submissive role wearing a spiked collar and leash. Her eyes have a black bar across them, again, so as to "conceal" her identity, the way they do in the fashion magazines, even though we the audience know exactly who she is. The other characters you mention apparently "gave their consent" to their image being shown.
Michael Albert