Earlier this year, it emerged that Mark Wahlberg had been paid significantly more to reshoot scenes for "All the Money in the World" than his co-star Michelle Williams, CNBC reported.
Smith's starring role on Doctor Who earned him a higher salary for the show, which reportedly had a budget of £100m, producers said.
As the show moves into the 1970s, Olivia Coleman will now step in as an older version of the monarch for the upcoming season three.
Not even the Queen is getting an equal slice of the pie but producers of The Crown say they will put that right next season.
However, given that Smith's role as Prince Philip was less central to the narrative than Foy's as Queen Elizabeth II, many viewers have been outraged by the revelation.
"Going forward, no one gets paid more than the Queen", executive producer Suzanne Mackie vowed at the conference, according to The Hollywood Reporter. Considered relatively unknown, Claire Foy had appeared in the Emmy-winning BBC mini-series Wolf Hall in 2015 along with a number of other roles in TV series and movies. So, for that matter, has Smith, 35, and nearly the entire cast.
She added that many women don't realise how much men get paid, and this may explain the imbalance on The Crown.
Representatives for Smith and Foy did not respond to CNN's multiple requests for comment.
Mark Wahlberg made news earlier this year when it was revealed that he was paid $1.5 million USA for reshoots on movie All the Money in the World, while co-star Michelle Williams received $1,000 US.