This is the comic that began defining what rules we could break in the universe of Emo Caveman and what rules we couldn’t.  You can see a bag of popcorn in the final panel as well as a pennant flag being waved.  Neither of these items could exist in prehistoric times.  But there was a sudden realization that because the story takes place before any history has ever been written down, that there were tons of possibilities for cracking conventional knowledge about the past.  Who is to say that early people’s did not invent popcorn and we just forgot how to make it until recently?  Why couldn’t pennants exist way back then?  Further and further questions like this came to us.  A paleontologist would call foul against this kind of thing, but our argument would be that they just haven’t dug up the world’s earliest bag of popcorn.  Also, there’s a lot that is already sort of silly in the comic such as talking animals and emo cave people.  So it feels fair game for the sake of satire anyway.  Once this was settled, we were liberated to write a lot more interesting stories.  There have been many cartoons and comics that have used the stone age as a setting, but we were discovering a bunch of things that have never been done before.

If you can do silly scenarios in way where it doesn’t bother the story or the audience, then you can get away with a lot of stuff like this:

http://peoplewhodrawstuff.com/the-bro-strikes-back/