When Kyra removes the cup that Riddick used to kill a guard on Crematoria, the cup has a badly broken and jagged rim and its handle is attached about an inch below the rim. In the next shot where the cup is completely visible, the cup's rim is less broken and jagged and its handle is attached at least two inches below the rim. The cup she places on the rock appears the same as it did when she first picked it up.
In the scene on Crematoria where Riddick is going to kill the guy with his "Tea" cup, he is obviously drinking something out of the cup. The final sip does not show him consuming the entire contents, but when he turns it upside down, not even a drop is left.
After Riddick is left on Crematoria by the Necromongers he takes shelter in a garage. Because the planet is quite obviously devoid of any humidity at all, the thin atmosphere does not transmit heat. Therefore, all shade on the planet, including the "night side" (the half of the planet that is in its own shadow) is much cooler. A similar effect can be seen in desert areas of Earth. Ironically, the extremes mentioned mean that the garage actually would require heating of its own to keep the occupants alive.
Upon approaching Crematoria in the mercenary ship, the crew states that the temperature on the sun side of the planet reaches 700 degrees and on the shadow side, 300 degrees below, yet they have no trouble traversing the terrain on the dark side, the 300 below side, in their regular clothes.
When the ship carrying Riddick is on approach to Crematoria, they're all just fine with the sunlight entering the windows. But once they reach the surface, suddenly the sunlight bothers them. The sun would have felt much, much hotter before they entered the atmosphere, it wouldn't wait until they reached the ground to start burning them.
When Riddick is crouched on a perch looking up at the Necromongers entering the atmosphere of Helion Prime, the digital addition of the 'shine' of his eyes doesn't match up with his eye and head movement.
After the Necromongers leave Riddick to die, he talks to the purifier. The purifier then walks out into the sunlight and his entire body bursts into fire and dissolves. But if you look at the bottom right of the screen, you can clearly see a skull and some other bones of those who died in the fight.