Well Done! And perfect for Halloween
What can I say? It was a great Flash. Atmosphere was perfectly creepy; animation was great; sound synch was right on - and you did it without a dialogue!
The only minor improvement I see would be a little bit more realism / flow when the characters were running. But even that minor flaw didn't really detract from the overall effect.
Keep up the great work - have you ever considered a series based on this? I think you could really do well by that...