The agreement - known as the USMCA - is up for a mandatory review next year. Carney has credited it with shielding Canadian businesses from the bulk of US-imposed tariffs on Canada.
Those underlying tensions seemed distant on Friday, when the leaders took the stage together to select the balls of their own countries from bowls, marking the beginning of a process to select groups for the initial stage of the jointly-hosted tournament.
The leaders' body language appeared cordial and warm. Collectively, they posed for a selfie with Fifa President Gianni Infantino on stage.
Reporters later saw Trump sitting with Sheinbaum, who had said earlier in the week that she planned to have a brief one-on-one with Trump to discuss trade matters, including steel, aluminium and automobile tariffs, on the sidelines of the event.
The Trump administration has largely backed away from threats to impose steep tariffs as negotiations continue.
Carney was sitting beside Sheinbaum. Both have expressed an interest in securing the future of the USMCA, which has been in place in some form since 1994.
Its fate is uncertain pending the outcome of the mandatory review due to be completed in the summer of 2026.
Trump also met for a brief 45 minutes with Sheinbaum and Carney on Friday.
In a statement, Sheinbaum said they talked about the World Cup and separately "agreed to continue working together on trade issues with our teams".
Carney's office said the three agreed to keep working together on the USMCA.