And here's the 'money shot'.

Mueller has practiced law and law enforcement long enough to understand the adage "don't ask questions you don't already have the answer to".

No doubt Trump's lawyers told him that too.

To which trump dumbly asks, "what, why would Mueller ask me questions unless he didn't have the answers?"

Face palm slaps from Trump's lawyers. "That's just it Mr. President, Mueller has the answers provided by your associates to grand juries, probably electronic transmissions and phone records too.....which means he will be looking for inconsistencies, contradictions nd lies by you

If your answers are at variance from what Mueller already has, yep, perjury, lying to a Federal official, are real dangers.