My favourite Hollywood hacking trope is the 3D model of travelling down a network cable as you hack in, as opposed to the reality of staring at lines of code for days at a time. That and opening folders that make every file in them open in sequence on the screen but always stopping at the exact file needed.
NCIS is possibly the worst culprit of all though. McGee, hack in to the CIA for me. (14 seconds later) Done Boss.