P0740 = TCC (torque converter clutch) enable solenoid Circuit
P0720 = Vehicle speed sensor malfunction
P0715 = Turbine sensor circuit malfunction
These codes indicate bad input/output sensors. But what concerns me is the big bang you heard. Usually with bad inputs/outputs you still have reverse and second gear. I might suggest dropping the pan and looking for metal piles or chunks in it.
You could just have bad input/output sensors. Or much worse, what could have happened, that big bang you heard could have been the torque converter, hence the TCC code, (it tried to engage and could not) and if it totally let loose, to where the ouput speed showed the vehicle moving at 60 MPH, but the input speed didnt match, it may have tricked the computer into throwing those two other codes.