Once Upon A Time In Mexico was director Robert Rodriguez’s conclusion to his Mariachi series. It took off where the last film Desperado left off and went with more action, more comedy, more drama. The main story was about preserving Mexico in the face of the devious Americans, ruthless drug bosses, and power hungry generals.
The mix of action and comedy is right at the start. A source named Belini (Cheech Marin) is telling CIA agent Sands (Johnny Depp) about El (Antonio Banderas) and his standoff with General Marquez (Gerardo Vigil). As the two confront each other, a little bar on wheels scoots out of the way to avoid the shooting that’s inevitably going to break out. El breaks out a guitar instead and begins playing like crazy, but it turns out to have a machine gun and a grenade launcher inside of it. That turned out to be an embellishment, so the story continues with El having regular guns on him, which he uses against the general’s men. Then She (Salma Hayek) arrives. The bar on wheels then scoots back out because the bar tender wants to get a look at how beautiful She is. Then the fighting starts all over again. The story is also integral to the plot. Agent Sands wants to hatch a coup in Mexico because that’s what the Americans do using El, General Marquez and a drug boss named Barillo (Willem Dafoe). Add to that She and the president of Mexico (Pedro Armendariz) and you have the story of how El Mariachi was going to save Mexico from dastardly plots both foreign and domestic. The light-hearted action and gun play would also be mainstays. That’s Once Upon A Time In Mexico in a nutshell. It's one of Rodriguez's best movies and by far the standout of the 3 part El Mariachi series.