When Wahl is in Schiff's Sail Loft we see the red digital clock in the background count down to 3:56. The camera then zooms in on the clock which has reset to 4:16.
In the climactic ending, a second tsunami is created to "cancel out" the first tsunami. In fact, the two tsunamis will pass through each other and continue on. At the point where the two waves meet, for an instant the height will be the total of the two waves.
During the big wave sequence, the tsunami breaks *after* it has already come ashore in one shot.