Aero-dynamics of Godzilla flying?

Perhaps some of the thrust emitted from his mouth is vectored out of ports located in his heels in the form of hot air (not flames). This would be enough to offset the thrust from his mouth and allow for backward movement without canceling the effect of the oral thrust, and ultimately, backward motion. This same technology has also been used in the NOTAR helicopter design, which vectors engine exhaust out of vents in the tail boom to counter the torque effect of the main rotor instead of an actual tail rotor. You can Google NOTAR for more details.