Fake American: Jack Thompson (Jack Jones) and Naomi Watts (Marie) are both Australian playing Americans with impeccable accents.
Hey, It's That Guy!: Quite a few in minor roles. In particular, Michael Wincott as Julius Bicke, and Mykelti Williamson as the head of the local Black Panthers group.
Too Soon: Defied; the studio had some questions about whether it would be a good idea to produce a film where the protagonist tries to fly a plane into a famous building just two years after 9/11, but Sean Penn persuaded them that it'd be a worse crime to screw around with history or chicken out of making the film altogether than it would be to risk offending some audience members.
Vindicated by Cable: Despite a generally positive critical reaction, the film's US release was so limited that it actually ended up making more money in the UK than it did its home country. Fortunately it's since found the recognition it deserves via DVD and reruns on television.