It's impossible to ignore a shout like that, particularly when it comes from the Captain. Chekov sees Kirk vault out of a vintage car and practically run over. He's a bit startles at first (why does Kirk seem surprised? Didn't they all end up here?).

When Kirk asks for a report, Chekov snaps to attention but seems a touch sheepish.

"I am sorry, Captain. It seems I arrived very unprepared."