Milo Ventimiglia was originally supposed to be Weatherby but dropped out because he didn't like the way the character was developed. He appeared in Stay Alive (2006) instead, another video game movie.
Robin Shou makes a cameo as a pirate. Robin Shou played Liu Kang in the 1995 film "Mortal Kombat" and it's sequel "Mortal Kombat: Annihilation", based on the video game created by Ed Boon.
When the girls are climbing to the top of the compound area individually, they are approximately 5 stories away from it. In the next shot when they all work together to get to the top, they are only 2 stories below.
When Weatherby is in the lab trying to free the trapped, Donovan is seen running from the Buddha head to the lab on the LCD screen. A few scenes later when he is encountering Helena, he is seen running from the Buddha head again.
When Helena is fighting all the guards on the staircase, there are knocked out guards and a samurai sword lying directly behind her foot. In the next shot, they are all to the side so that Helena can run down the steps.