Continuity mistake: When Sommerfield is talking to Blade about Daystar and says to him "we're calling it Daystar", Sommerfield is standing opposite Blade. In the following shot she moves to standing by his side, then back to where she was. (00:49:35)
Blade: Trinity (2004)
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Directed by: David S. Goyer
Starring: Ryan Reynolds, Wesley Snipes, Jessica Biel, Kris Kristofferson, Parker Posey
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Answer: It's possible that he followed one of them back to the base. This is feasible since they wouldn't be able to tell that he was following them because of his shape-shifting abilities.