Gregory Porter, Derrik Sweeney and Luke Gates were accused of throwing firebombs at police last week and thrown in jail.
They denied the charges.
An Egyptian court ordered their release Thursday. All of them arrived home Saturday night.
On the night of their arrest, Sweeney said he and the others were told by a group that they would be led to a safe place amid the chaos engulfing Cairo's iconic Tahrir Square.
Next, he said, they found themselves being taken into custody, hit, and forced to lay for about six hours in a near fetal position in the darkness with their hands behind their backs.
The worst, he said, was when they were threatened with guns.
"They said if we moved at all, even an inch, they would shoot us. They were behind us with guns," Sweeney said, adding that the first night of detention was "probably the scariest night of my life ever."
However, he said the first night gave way to much better treatment in ensuing days. Sweeney didn't elaborate on who he believed was holding him the opening night but he called the subsequent treatment humane.
Meantime in Egypt, activists are calling for another mass rally in Tahrir Square.
The protestors want military rulers to step down in favor of a transitional government.
In response, military rulers issued a stern warning Sunday, saying a failure to solve the current crisis could result in "extremely grave" consequences.
All this comes ahead of Monday's parliamentary elections. It'll be the first vote since the ouster of former President Hosni Mubarak.
The Associated Press contributed to this story.