Charlie Brown doesn't have nearly the fixation on D. Crockett as Schroeder does on Beethoven, but his embarrassment makes the strip.
At first this seems like another joke on the size of C.B.'s head, but really any of the characters could see around that thin tree. The angry look on Lucy's face is adorable.
There are a handful of strips that establish that Schroeder isn't simply a child prodigy, but actually has a music career. Lucy's general apathy towards music makes her choice of crush an odd one; Schroeder doesn't actually have much personality other than his music.
The first line drive Charlie Brown ever dodged (although it looks more like it bowled him over, dodging is how it's described in later strips).
This is more of a Lucy kind of strip, but neither her right field position nor her incompetence at baseball have been firmly established yet.
For some reason, I can easily imagine one of Thurber's dogs in Snoopy's place here.