Several fans had pointed that out a while back. I suppose one could rationalize it on the grounds that Doc didn't tape it back up evenly, thus leaving some parts out, although that could be seen as stretching it.
In regards to the note, storyboarder Andrew Probert takes credit for a last minute change to Doc's discovery of it; intially after finding it and tearing it up, he was to storm all the way across the street and toss the pieces into the Packard's ashtray. When drawing up this scene, Probert realized doing it this way made it a little too obvious that he'd retrieve and reassemble them later. He approached both Bobs on the matter, they agreed with him, and so in the final version, Doc casually shoves the pieces into his coat pocket before charging up to the top of the courthouse to fix the large problem at hand (out of sight, out of mind, I guess).
