Once you have returned the tickets to the man who lost them, use the one he gives you. (see related question)
During the Tour, you can recover the torn picture piece. At night, you use the pieces to open the lock and enter the museum from below.
You use it.
If you have entered it from the tunnel system then you can exit it the same way. if you have entered it from the door you can use the door. if you need to get into the supply room you have to get a job first which means you have to talk to the assistant curator. once you get the job he will give you a key to the supply room. i hope your question was about counterfeit island. also i hope this helped.
Once you get the key from the curator, go back to Counterfeit island and use it at the Inspector's house.
dig in a trash can and there is a ticket. the character wont let you use it
You use the key from the Curator to unlock the Inspector's house in the CountrySide.
The Underground Tunnel Tour tickets are in the bottom of the second large trash can near the tour entrance. You cannot use them immediately because they are not yours. You will find the owner of the tickets in the Internet Cafe on Main Street. But before going there, get a green balloon from the Clown Store and take it to the Countryside. The result will ensure that the owner of the tickets is not too preoocupied to talk to you.
You don't ever even use the boat.
You have to use a gameshark
Go back to Counterfeit Island and use it to open the Inspector's house in the Country Side. On the way, the street artist gives you a clue as to what to look for in the house.
When you get past the Black Widow's guards, then you will use it to enter her layer. Have fun! :-)