Stephen Sommers deliberately chose to avoid the style of transformations from other werewolf films, where the character would usually grow hair as part of the change. Instead the decision was made to have the character rip his skin off to reveal the werewolf form underneath, going with the idea that the beast "comes from within".
The place where Van Helsing and Anna fight Dracula's three brides is the same place where Frankenstein (1931), Dracula (1931), and Le Loup-garou (1941) were filmed. The set is called the Court of Miracles, and it's part of the studio tour at Universal Studios Hollywood.
Stephen Sommers wanted Kate Beckinsale for the role of Anna, but feared it was too similar in tone to the vampire/werewolf film Underworld (2003) which she was shooting at the time, and he didn't ask her. Eventually her agent got Sommers to send the script, and Beckinsale immediately signed on.
In interviews, Kate Beckinsale has said she hated the corset she had to wear for most of the shooting. When the film finally wrapped, she wanted "to burn it all".