Milly Alcock's Supergirl costume is reported to have a connection to Christopher Reeve's Superman, with some outlets suggesting that the cape contains fabric from Reeve's 1978 Superman costume. The connection is described as a tribute to Reeve, with details of the costume said to be emotionally significant. The exact nature of the connection is not universally agreed upon, but it is characterized as a way for the Supergirl production to pay homage to the iconic Superman actor.