His most significant achievement in film was Oro, Plata, Mata, which he directed after winning a scriptwriting contest sponsored by the Experimental Cinema of the Philippines.

Upon moving back to Manila, he got involved in television musicals and eventually co-directed the film Binhi with Butch Perez.

[1] He also directed the movies Virgin Forest, Scorpio Nights, Unfaithful Wife, and the "Manananggal" segment of Shake, Rattle & Roll.

Gallaga and Laida Lim-Pérez won Best Production Design for Eddie Romero's Ganito Kami Noon, Paano Kayo Ngayon?

[citation needed] Gallaga and Reyes won Best Director and Best Screenplay for Magic Temple in the 1996 Metro Manila Film Festival.