* CastingGag: Brendan Gleeson plays Liam Tobin. He had played Michael Collins himself in a film called ''The Treaty''.
* DawsonCasting: Liam Neeson was in his forties playing Michael Collins from his late twenties to early thirties.
* FakeIrish:
** Julia Roberts as Kitty Kiernan, Ian Hart as Joe O'Reilly, Aidan Quinn as Harry Boland.
** Alan Rickman as Eamon De Valera is a curious case. He was half-Irish, half-Spanish and born in New Jersey. WordOfGod even said that the character was better played by a non-Irish actor to get a more rounded performance.
** Liam Neeson is also Northern Irish, playing the Cork native Michael Collins.
* ProductionPosse: Neil Jordan regular Stephen Rea - who he worked with in ''Film/TheCompanyOfWolves'', ''Film/TheCryingGame'', and ''Film/InterviewWithTheVampire'' - plays Ned Broy.
* RealLifeRelative: Aengus O'Malley, great-grandnephew of the real Michael Collins, plays a student in the scene at Marsh library.
* TooSoon: During filming, the IRA ceasefire ended when a bomb was exploded in London's Canary Wharf. As a result, the ending was re-shot to focus more on the love story between Michael Collins and Kitty Kiernan - and downplay the breakdown of Anglo-Irish Treaty negotiations.
* WhatCouldHaveBeen:
** Michael Cimino was attached to direct the film for a while, and Gabriel Byrne was his choice for the lead.
** Mary Louise Parker was on the verge of signing on to play Kitty when Neil Jordan heard that Julia Roberts was interested in the role.
** The film had been tossed around since the 60s, with Richard Harris expressing interest in playing Michael Collins in a biopic. Robert Redford was also briefly inspired to do the film in the 80s and went to Dublin to research for it. Kevin Costner had likewise been interested.
** The film was going to be released with a 15 rating in Ireland. But the censors decided to release it with a PG, despite the violence, for its historical significance.