The buttons on KITT's main panel seem to change. The button immediately below the "Turbo Boost" is normally "Eject Left" but changes 3 times in this episode. It is shown as "Zoom In" (though there is no zoom out button), then it changes later to "Ultrasonic Freq" (plus wrong typeface), then "Auto Roof Left" before returning to "Eject Left".
When Kevin is knocked off the building, it can clearly be seen that the railing doesn't get bent. Later, when Michael visits the site, the same spot has a massive dent in the railing.
When Michael is on the phone with Hannegan, he is holding the phone in his right hand and the photo of Hannegan and Soltis in his left hand. When it cuts to the close-up of the photo, it is in Michael's right hand. When it cuts back to Michael, the phone is in his right hand and the photo is back in his left hand.
After breaking in to the construction site, Michael drives to Janet's house: when he gets out of KITT and walks to the house you can see the top of a head moving under the driver's seat, plus in the next frame you can see an arm.
Obvious dummy used for Kevin when he's knocked off the building in the opening scene.
When Michael reverses out of the semi at night to head to the construction site, KITT says to Michael "I've never seen Devon so upset" and you can clearly see that KITT is incorrectly in AUTO CRUISE mode, despite Michael driving. A few seconds later, when KITT talks again, he is now correctly in NORMAL CRUISE mode.
When Michael starts to follow Steven Barnes, KITT's speedometer and tachometer stay at "000".
When KITT turbo boosts through the crane control room, the room is clearly empty, despite being shown to contain control panels, monitors and other equipment just seconds earlier.
When KITT backs into & gets stuck in the mud, it is obvious that its a toy car.
When Mr. Knight asks K.I.T.T. where the likely location of any bugs in the building might be, K.I.T.T. displays an image while Mr. Knight has barely started asking the question.
When Michael sees Steven Barnes exiting the office, he says "Well, well, well, looks who's here..." and opens KITT's door. As he gets into the car, the entire camera crew is reflected in the door.
When Michael is climbing the railing at night at the construction site, he is clearly wearing a safety harness - the rope is visible dangling next to him.
When Michael throws the rope over the edge to escape the building, he doesn't actually tie the other end to anything.