The 2002 sci-fi film was directed by Steven Spielberg and starred Tom Cruise, Samantha Morton along with Farrell.
Though Bardem revealed he was a big fan of Spielberg, he said he wasn't prepared to board the film at the time, according to The Hollywood Reporter.
"When I met him (Spielberg), I was really star-struck," Bardem recalled when delivering a master class at the Toronto international film festival.
He added, "But at the time, it was difficult for me to jump into a foreign language performance. My English is better now. You may not believe it, but it's better."
The festival runs through to September 17.