this is when Mikuru first uses her MIKURU BEAM, not later when you see the crappy special effects. If you remember her first confrontation with Yuki, Mikuru fires the beam but there is a sudden reaction from Kyon, as if he was hit, and the camera blacks out for a second. Then the scene shows Yuki pounce on Mikuru as if she wanted to beat her senseless. It is said somewhere that perhaps Mikuru actually fired a MIKURU BEAM because Haruhi expected her to in the movie. LOL!!

The cat is a stray which Haruhi found and made Kyon adopt, giving it the name "Shamisen". It lives with Kyon and is the playmate of Kyon's little sister who affectionately nicknamed him "Shami". During the filming, he suddenly started talking during an exchange between Yuki and Mikuru, most probably because Haruhi unconsiously wanted him to (though for what reason I'm not too sure since a talking cat wouldn't make much sense right there and then, unless Haruhi thought a witch had to have a talking cat?). You could hear Itsuki in the background telling the cat to stop talking.

.....they had, in the novels. Not sure of the details myself but apparently Kyon has timetravelled to 3 years prior to starting High School to meet with Haruhi. He used the false name John Smith.

You can still access Nagato Yuki's page, though. People are speculating that is has something to do with what happened in the novels on December 18...

....everything was fixed and back to normal 3 days later, thanks to Kyon, Mikuru and Yuki's intervention.

.....the SOSdan insignia Haruhi made and Kyon added to the website became all fuzzy looking in the episode, and on the actual website too. Only afterwards did it change back. I read that looking at or changing the code causes the message "data corrected by Nagato Yuki" to appear somewhere on that page as well.

.....there wouldn't be a website if there wasn't an SOSdan in the first place.