He goes to the shop at night (after 2am) to purchase alcohol when the fire happens. There is nowhere in any of the surrounding areas you can purchase alcohol at that time. Even if he drove to Boston and back (which would take 2 hours not the 30 minutes stated) I still doubt he could purchase alcohol at that time. It's not legal in Massachusetts.
Michelle Williams was nominated for a Best Supporting Actress Oscar for her role as Randi Chandler, even though she's only in the film for 12 minutes.