Throughout the entirety of the film, Superman is never directly addressed as such. When other characters speak with him or refer to him, they either use "Clark," pronouns such as "him," or other terms often used to describe Superman's public image.
Although never directly stated, Gordon's wife in this story is Sarah Essen, the woman that he has an affair with in "Batman: Year One (2011)." He calls her Sarah when sitting in bed next to Barbara.
During the fight between Superman and Batman in crime alley, a framed picture of Christopher Reeve's Superman can briefly be seen in one of the rooms.
Commissioner Gordon's wife Sarah was never actually illustrated by writer/artist Frank Miller in the source material. When she finally appears at the end of the series, she is in silhouette.