Factual error: The address on Claire's business card reads 514 West 43rd St. When Frank gets there, the street sign is for 3rd St./900 East block. The sign on the building reads "9th Street Temporary Shelter". Along with these discrepancies, taking into consideration that 3rd St. may be the cross street, WEST 43rd would not cross 3rd St. EAST, as they are on opposites sides of Manhattan. Even if the '4' on the sign for 43rd St. were somehow obliterated, 514 still would not be on the 900 East block. (00:53:10 - 00:54:15)
Factual error: The Ghost of Christmas Past takes Frank to the year 1969, where he watches his younger self giving Claire a set of twelve Ginsu knives on Christmas Eve. Young Frank even remarks that the Ginsu knives are sharp enough to cut through a tin can as easily as a tomato. Problem is, Ginsu knives didn't arrive on the market until 1978, which is when the tin-can-cutting demonstration was first used.
Answer: It's a vision, not reality, so one could interpret it either way. I think it's more powerful if Calvin is seeing Frank, silently accusing him of being (at least partially) responsible for his (Calvin's) situation.