Just to be clear the Continental accident in the pictures was not a towing issue and the story in front of those pictures is made up.

There was an incident a few years ago where two guys were supposed to tow a jet across the apron to a gate, IIRC this was at MIA, they got to the aircraft and discovered that the towbar was missing, rather than go back to the shop for one they decided to run the plane over to the gate under power, however they forgot/didn't know to also power the APU so there was no hydraulic pressure to run the brakes...