Easter egg: Go to the commentary menu on Disc 1, highlight Off for the second commentary, and hit right, then up. A yellow spider should appear. Hit enter to see a funny introduction with the director.
Easter egg: In Disc 2 of Spider-man 2, go to "Gallery", when your cursor is on "Proceed", hit the up button on your remote, and click on Spider-Man's Spidey sense. You'll go to a clip of Alfred Molina lightening the mood in the studio.
Easter egg: In the Spider-man 2 widescreen Disc 2, under the "Making the Amazing" sub menu, a picture of Doc Ock and his tentacles are in the background. If you click the upper left tentacle (using a DVD-ROM on a computer) a clip of Willem Dafoe pretending to be Doc Ock is shown. When using a normal DVD player, you can use the arrow keys. When "Play All" is selected use the arrow-up key once, the upper left tentacle turns green, then click "Enter" and you will see the same clip.
Answer: While it's never mentioned in the film, the most likely explanation is that Harry, as a rich kid, grew tired of "slumming it" and decided to move back into his mansion.