In the first scene, Cydney hangs her feet out of the jeep and they are almost hit by a tree while passing. A short while after, it is noticeable that she has red nail polish on her toenails. However, later on in the movie, in various scenes that show her feet, she no longer has nail polish.
The headrests in Cliff and Cydney's Jeep are missing during interior shots then reappear during long exterior shots. Removing headrests from seats has been a common practice in movies for decades in order to provide more visibility while filming inside automobiles. This can usually be spotted by the two mounting holes at the top of the seat which are visible once the headrests have been removed.
When Nick and Cliff go 'hunting' it is pouring rain. When Cliff returns to the campsite he is completely dry and his hair is perfectly unscathed, however when Nick returns he is partially wet.
At.the waterfall scene Chris Hemsworth's first shots are revealing low riding shorts for eye candy. His hands are holding his shirt around his neck as the shot bounces back and forth. On the last view back to Chris the shorts are at normal waist level.
While in the sea cave, Nick says "What we have here is failure to communicate" and attributes the line to Paul Newman in Cool Hand Luke (1967). The line is most notably spoken by Strother Martin, but Newman's character DOES actually say this line in the film, mocking Martin's character.
A double rainbow is shown with red on the outside and violet on the inside of both rainbows. In reality, the order of colors in the outer rainbow is always reversed, with violet on the outside and red on the inside.
After checking out the video camera, Gina tries to call Nicko but her phone's caller ID appears t say "Micko". But the font says Nicko.
When Gina climbs the vines at the cliff beside a waterfall after seeing what is on the video camera. There is a knotted rope among the vines. In fact at the base before climbing, the green colored hawser laid rope can be seen. At the top, the rope can be clearly seen, passing over a rock.
Later on, she descends the vines and the rope is clearly seen.
The Sea Cave scene: the rocks in the cave are limestone. Limestone is absent from the volcanic islands of Hawaii (but very common in Jamaica, where the scene was shot).
The Royal Caribbean cruise ship Explorer of the Seas is clearly visible as being in port at Oahu. Explorer of the Seas has not been to Oahu, however it has been to Puerto Rico, where the movie was filmed.
The rocks in the cave are limestone. Limestone is absent from the volcanic islands of Hawaii. (But very common in Jamaica, where the scene was shot).
A previous Plot Hole mentions that since Cliff threw away the tape from the digital camera into the sea, Gina could not have seen the photos on it. When Gina first looks at the camera, it clearly shows her pushing in the SD card all the way, which revealed the photos on the SD card to her. Cliff even says in an earlier scene that he should read the camera's manual, so it's clear he did not know it also had an SD card in it.
Gina discovers that Cliff and Cydney are not the people in the camcorder pictures, when she takes the camcorder and looks at the contents. She knows now that it must be the material from the victims and that Cliff and Cydney stole their camera.
This does not sense, because there should not have been any material left on the camcorder, because we see in the flashback that Cliff throws away the tape in the sea after they took the camera.
This does not sense, because there should not have been any material left on the camcorder, because we see in the flashback that Cliff throws away the tape in the sea after they took the camera.