The real Brycen Newman is in multiple scenes in the movie: he is baseball player "#4 Lombardi"; he is a football coach in the weight-lifting scene; he is in the prayer scene right below the actor playing him; and he plays an orderly in the hospital.
The "real" trip that Brycen Newman missed was not to the California Baseball Championships; his high school won that with the walk-off double he hit in the game. The real trip he missed because of his brain cancer was a trip to represent America in the 15U World Championships in Nagoya, Japan that year. He was playing on Team USA-San Diego.
Two students from Cathedral Catholic High School were in the cast: Lauren Owens played Riley and Breanna Laureti played Lucy.
The football field where the football scenes were filmed is the same football field, "Manchester Field", where Brycen Newman's football teammates revealed that they had all shaved their heads in team spirit with Brycen going bald from treatments.
The baseball field where the baseball scene was filmed is the same baseball field where Bryce Newman hit the walk-off double in the 11th inning to bring home the city championship for Cathedral Catholic High School's freshman team. That was the first freshman baseball championship his high school had won.