After Terry falls out of the boat on Little Niagara, there is a quick wide shot of the boat showing all four people still in the boat.
Tom falls into the water from a cliff after being shot at and emerges soaking wet. A minute later his clothes are dry.
When Terry tells Tom that his "sister" is from Tulsa, he is sitting down at the edge of the water. In the next shot, further away, you see him half standing up and bending over.
Raft goes through huge rapid, drops over the falls and should be full of water and have to be bailed. A minute later when the raft is lifted by the cable it is dry.
Although Wade's revolver holds 6 cartridges, there are 7 shots: 1 shot at Maggie (the dog), 1 when Tom tries to get the gun from Terry (waking Wade), 2 more at Tom on the ledge, 1 when Wade shoots Ranger Johnny, 1 when Wade drops the gun into the water near the end, and Gail's final shot. Also, earlier Wade removes 3 spent cartridges, leaving 3 in the chamber, but when Gail opens it up, there's only 1 in the chamber.
At about 1 hour 28 -a dog cannot swim as fast as a human.
One could never start a fire with the tiny magnifier that folds out of a pocket knife.
When Tom loses his grip on the cliff and plunges into the river, the cliff face is actually gray fabric painted to look like rock. If you look carefully, it moves and bounces like fabric as he rolls down it.
From 0:25:02 -the raft has obviously been tethered to a stationary object; as it is no longer moving with the current.
At around 26 minutes -when Tom saves Wade from drowning a float is seen mid screen and a rope is seen draped over the oar on the right side of the screen. These items suggest the use of underwater netting to aid the actors.
After Tom jumps off cliff into the river he coaxes the family dog, a yellow lab named "Maggie", into jumping in after him. Throughout the entire movie the dog is called "Maggie" and referred to as "girl" but when the dog leaps from the cliff into the river, you can clearly see it's a male dog.
Throughout the movie, Gail warns the bad guys that there's no way out of the canyon other than via the Gauntlet, which only she can navigate. But Wade threatens to shoot her anyway. Moreover, Tom, the dad, runs ahead the boat and past the Gauntlet.
It is quite surprising- how Tom is able to get so far ahead; considering the facts that the raft is so much faster and travels a much shorter distance while he has to climb up and down cliff faces and rock formations.
It is not explained -how the park ranger is able to paddle his canoe through all the difficult rapids while remaining unharmed.
The further down the river they travel the more stuff they have.
Throughout -for some reason no one is able to untie a knot.