If I go there Friday (24) just to see the mirrored room can I go inside? I didn't know we should buy tickets and it's my last day on US. :(

Go early and sign in for the room as early as possible. Hopefully the wait won't be so long. Be sure that you enter your info correctly as that is how they will contact you to let you know to queue up.

Go early (before 11 am) and you should be able to sign up for the infinity room que on the iPad inside. After that it's about an hour wait or so and you can check out the museum's other exhibits. Also online you can reserve tickets for free to enter the museum. Just reserve them today.

You can still go on their web site and see if there are any places left to reserve. If it is full on Friday the only chance you'll have is to stand in line and hope that it is someone that doesn't show up.