This is just weird.
If you watched McCain's speech (I didn't), you might have thought he was speaking in front of a green screen, until they pulled out to a shot of some big, Georgian-looking building. What was it? A mansion? A government building? No, it was a middle school in North Hollywood that happens to be named "Walter Reed Middle School".
Why was it up on the screen? No answer yet from the McCain camp, but Josh Marshall wonders if they told some flack to find a picture of Walter Reed Army Hospital, this is what they found, and nobody caught the mistake. At the moment, that seems to be the most reasonable explanation.