Just watching BTTF, noticed something here that makes me think that the "inaccuracies" of the courthouse might have been totally on purpose. The statues first were of dogs that looked suspiciously like Einstein. Considering that Edna was spearheading the idea of getting statues mounted on either side of the clockface, she would've picked something that she felt would "inspire" (read: terrify) citizens. In her case, dogs. Now, it could be that the statues on the courthouse were damaged or destroyed prior to 1955, which certainly seems to be the case now as they were both knocked off. Or someone suggested that lions or whatever would work better. Another thing was the ledge itself. It extends too far out. Now, we've learned that Emmett went up there sometimes to think, to be alone. However, he's nearly killed that way. Perhaps he did that in the original timeline, someone decided that the only way to keep that from happening would be to reduce the size of the ledge to keep anyone from being dumb enough to climb out there. This would also explain Doc's reticence as he climbed out on the ledge.
I've outlined where the Einstein statues were, where the lions are going to be, and where the ledge SHOULD end by 1955.
"Geez, we've been back together for five minutes Doc, and you're already talking about the end of the universe."
"Stupid, stupid rat creatures!"