September 8, 1953: Two bears fighting

Here, Charlie Brown and Lucy's roles are neatly reversed from their later personalities. That look in Lucy's face in particular is one she never seems to adopt later. It's an expression that only rarely shows up in Peanuts, but it does happen once in a while.

October 18, 1951: I'm sure Hobbes could think of something

I've mentioned before that, as I go through these, at times Calvin and Hobbes seems like it must have been directly inspired by early Peanuts. The characters are of similar proportions to the kids in C&H, and this bath-avoiding trick could have come directly from Calvin's playbook.

It's not a sure thing, but it does seem like it might be possible.

November 7, 1950: Maww mcmaww mra-aww

A rare adult-spoken word balloon.  In television peanuts, these were usually presented as muted trumpet.

Also, this one makes it less obvious that Shermy is Snoopy's owner, although that impression gets reinforced later.  To be torn down again.  Really, it's hard to get a fix on Snoopy's owner until the strip starts to take its backstory more seriously.