Revealing mistake: During the night surfing scene notice that the sun is evident in the background (look closely it does not appear long). There are also shots where you can see clouds and faint blue sky. Moments later you see Keanu and Lori sitting in the water with completely different lighting which was actually taken at night and further distinguishes that the surfing shots were not actually done at night time. I heard the scene was shot during the day with a filter so it looked like it was shot at night.
Continuity mistake: During the scene where Utah is chasing the ex-president, we see Ronald Reagan run out of a house and scale a fence into a neighbours garden, instead of running down the driveway. The next shot then shows Utah running out of the house with the fence coming into view, but without seeing the ex-president, and then give chase over the fence. He wouldn't have known to jump over the fence, because he wouldn't have seen him go over it.
Visible crew/equipment: When Johnny Utah jumps out of the plane in the last free fall scene, he jumped out without a parachute. If you look closely, you can see that the stuntman who did the jump has a huge parachute on underneath his shirt.
Continuity mistake: At the bank, when Keenu gets shot in the vest you see him take off the vest and clutch his chest. Then as Swayze walks up to him to knock him out he is wearing it again.
Continuity mistake: In the night surfing scene, as Johnny gets up for the first wave, he is riding regular (left foot forward), but as the camera cuts back and forth he jumps back and forth between this stance and goofy (right foot forward). All other surfing shots of Johnny in the movie show him surfing goofy.
Continuity mistake: In the first sky diving scene all of the ex-presidents have joined hands waiting for Johnny Utah to join them they then cut to a close up of Johnny Utah and then a shot from behind Utah trying to reach the group which is not holding hands anymore for about 2 seconds.
Other mistake: In the fight scene where Bohdi helps special agent Utah you see that his surf board gets broken in two and then after the fight he is seen leaving without the board, but in the scene where he and Tyler are woken up early to go surf right before Tyler says "you look like you just saw a ghost" you see him carrying the same board.
Continuity mistake: As well as the afore mentioned blonde/black hair on the computer screen we also see green eyes on the screen but Angelo reads out 'blue eyes'.
Continuity mistake: When Gary Busey looks at the computer description it says Lori Petty has black hair, but when Keanu Reeves looks at it, it says she has blond hair.
Continuity mistake: In the last jump scene with Patrick Swayze and Keanu Reeves, when they need to pull the cord and Keanu has to hold on with both hands, it cuts to a shot where Keanu is not holding on at all.
Other mistake: When the guy shoots himself in the foot, there is a close up of the gun as it fires. If you watch it in slow motion you can see that when the gun fires it's pointing outwards, not at the guy's foot.
Factual error: In the second skydiving scene Patrick Swayze tells the pilot to fly the plane at 4000 feet, which he does as this can been seen on an altimeter. When skydiving from 4000 feet it would take 25 seconds before you hit the ground but the skydive in this scene lasts 1 minute 51 seconds.
Continuity mistake: In the final skydiving scene, Johnny Utah is holding his gun on Bohdie in his left hand. A shot from above them during the fall shows Utah holding the gun in his right hand. Much is made about how Utah can't switch hands.
Deliberate mistake: When everyone is surfing at night, the sound of the waves in the background is significant, as it should be. However, at one point, when Keanu and Lori are having an intimate conversation on the water, the sound of the waves disappear. The wave sounds resume in the next scene.
Factual error: There is no way Utah could have gotten information about Tyler's parents' death, let alone the city and year, from the computer he was using at the FBI office. He would have had to run a separate search for that information using other sources. That type of personal information is not contained in any crime information database.
Continuity mistake: When Utah is playing football on the beach with Bodhi, and his buddies and Bodhi makes a catch, he begins running down the beach towards the endzone. Utah can be seen giving chase and checking the same two people twice.