Hand brake failure.

[426Cuda]

Why didn't you put it in park first up? Never trust any handbrake. They're a secondary backup only.

 

[lmfvf2ssredlineute]

best thing to do with a auto especially when stopped parked on a hill is to first select neutral with foot still on the brake, then apply the hand brake, then take your foot of the brake so the vehicles rolling weight is taken up by the hand brake then select park
doing it this way you make sure the autos not holding the vehicles weight which can damage the auto, park is only a safety back up for the hand brake