In Robert Wuhl's apartment, there's a poster on the wall that looks like a poster for Batman. Robert Wuhl played Alexander Knox in Tim Burton's "Batman" (1989).
There are 5 flags flying outside the hotel. (From the left) The first, third, and fifth flags are easily identifiable as USA, Poland, and Hungary respectively. The second is reminiscent of East Timor and the fourth seems to be a simplified version of the Portuguese flag.
Although never identified by name, the hotel in which the family is staying is the Plaza Hotel.