After the villains have been defeated and the League stands triumphant, we get a quick shot of the SWAT van waiting to take them to prison. However, Copperhead, who's already in police custody, is in the van along with Cheetah, Star Sapphire, Solomon Grundy, and the Shade.
When the Joker goes to kill the unguarded and (he thinks) trapped Batman, and Batman gets the drop on him, Batman is wearing his utility belt. The belt was taken from Batman brought to the upper levels where it was compromised, so it is extremely unlikely that he would have been able to recover it.
Luthor picks up a sofa and smashes a monitor after the bomb failed to destroy the Justice League, but in the next scene, the monitor is intact. It was even used to show Cheetah kissing Batman after it was 'destroyed'.
Superman and The Flash try to force the location of the villains' base out of Copperhead, but Copperhead isn't talking. Although J'onn is a telepath - and could pull the information directly from his mind - this isn't considered, likely due to J'onn's sense of ethics.