Corrected entry: When Sonja is being executed by sunlight and Lucian is chained before her, he isn't wearing his spiked collar, which is the only thing that could have prevented him from morphing in to his lycan form, breaking the chains and saving Sonja. As the scene was shot (without the collar), he could easily have transformed, broken the chains, and saved her.
Corrected entry: When the vampires chasing Lucian during the first escape are exposed to sunlight, they vaporise immediately. However, possibly for dramatic purposes, Sonja does not disintegrate (only badly charred) when she is exposed to sunlight.
Correction: Because Sonja is Viktor's daughter and is an older vampire than the vampires chasing Lucian. As such, she is going to be much stronger and it will take more to make her disintegrate. This is the same as when Selene is exposed to sunlight in Underworld:Evolution. Both Sonja and Selene are direct fledglings of Viktor, and so their vampire blood has not been diluted by intermediaries.
Corrected entry: Sonja's eyes change color constantly throughout the movie. Sometimes they are the pale blue color of the other vampires, and sometimes they are her natural brown color. All of the other vampires have various shades of blue.
Correction: The eyes of the vampires in the Underworld universe change when they are in a heightened state, such as fighting. Selene's eye's in the first two movies changed color as well, most noticeably when she shoots the lycan that was lying on the ground in the tunnel scene at the beginning. When Sonja's eyes are brown, she is not doing anything vampiric, and acting more human. They turn blue when she fights and acts like a vampire.
Corrected entry: When Victor tore the necklace from Sonja, it appeared to have been broken off with only the pendant remaining. Next shot, it has a chain attached. (01:13:15)
Correction: When Viktor ripped off the pendent there were a few links from the necklace attached to each side.
Correction: They left those silver spikes in his back, & that is why he was unable to transform & save her.
He was only whipped right before they walked out and closed the door, so the roof could be opened. If the spikes were in him at all, he wouldn't have been able to change later and break free.