Maybe that wasn't the National Anthem after all?

http://en.wikipedia.org/wiki/National_anthem_of_South_Vietnam

Youth of Vietnam, arise! And at our Country's call
Single in heart let us open the way; let us keep in mind
Our millenary history. From North to South, brothers,
Let us unite. Our young hearts are crystal pure;
Unsparing of our ardent blood, let our efforts increase.
No danger, no obstacle can hold us back.
Despite a thousand trials our courage is unshaken.
On this new road our eyes embrace the horizon,
Our soaring youthful spirit is undauntable.
Youth of Vietnam, to the very end! this we resolve.
To give ourselves completely, this we vow.
Forward together for a glorious life,
Remember we are the generation of the Lac-Hong.

Oh citizens! Our country has reached the day of liberation
Of one heart we go forth, sacrificing ourselves with no regrets
For the future of the people, advance into battle
Let us make this land eternally strong
Should our bodies be left on the battlefields
The nation will be avenged with our crimson blood
The Race in times of crisis will be rescued
We the People remain resolute in our hearts and minds
Courageously we will fight such that everywhere
The Glory of the Vietnamese resounds for eternity
Oh citizens! Hasten to offer yourselves under the flag!
Oh citizens! Hasten to defend this land
Escape from destruction, and bask our Race in glory
Be forever worthy of the Lạc Hồng descendants!

http://www.lyricsondemand.com/miscellaneouslyrics/nationalanthemslyrics/vietnamnationalanthemlyrics.html
Soldiers of Vietnam, we go forward,

With the one will to save our Fatherland,

Our hurried steps are sounding on the long and arduous road.

Our flag, red with the blood of victory, bears the spirit of our country.

The distant rumbling of the guns mingles with our marching song.

The path to glory passes over the bodies of our foes.

Overcoming all hardships, together we build our resistance bases.

Ceaselessly for the people's cause let us struggle,

Let us hasten to the battlefield!

Forward! All together advancing!

Our Vietnam is strong, eternal.

Soldiers of Vietnam, we go forward!

The gold star of our flag in the wind

Leading our people, our native land, out of misery and suffering.

Let us join our efforts in the fight for the building of a new life.

Let us stand up and break our chains.

For too long have we swallowed our hatred.

Let us keep ready for all sacrifices and our life will be radiant.

Ceaselessly for the people's cause let us struggle,

Let us hasten to the battlefield!

Forward! All together advancing!

Our Vietnam is strong, eternal.

These are not the words I remember.
Trying to find those we saw last night.