Here’s how he “secretly” went to Prague.
He crossed into Mexico illegally where he boarded a private jet and flew non-stop to some obscure private landing strip where no passport was ever checked. Then, on his way back, he flew back into Mexico to another obscure private landing strip where he was met by professional human smugglers and whisked back across the border.
/sarc
It was not a private jet - sheesh! it was the same SR-71 G.H. Bush took ... you gotta keep up!