Continuity: When fighting with Watson on the stairway, Mr. Smith's hair is in his face on the closeup shot but is otherwise greased back.
Factual errors: Watson says he's from Santa Maria, which is near Lompoc (California), pronouncing it "lom-pock". If he actually lived there, he'd know it's pronounced "LOM-poke".
Continuity: The writing on the business card Watson attempts to hand the cab driver differs before and after the hand-off.
Continuity: When Watson pulls the Governor's picture from the envelope, we can see through the photo, revealing that the face is visible to him. In the next shot, Watson starts pulling when only the hairline is visible.
Factual errors: Watson's business card lists a Santa Maria (California) address. Santa Maria is in the 805 area code, but the phone number on his card has a 310 area code (Los Angeles).
Crew or equipment visible: At Union Station, when the security guard attempts to stop the rollerbladers, film lights can be seen through a window on the right.