Creator Backlash: After Man of Steel came out Bryan Singer commented on both that movie and this one. He is proud of what he made, but has expressed understanding of why audiences weren't as enthusiastic about it. In retrospect, he would have increased the action quotient or sped up the pacing (putting the airplane catch earlier in the movie), or else done a complete reboot. Beforehand, other people involved with the production expressed similar sentiments.
Dawson Casting: Inverted. In spite of this film taking place five years after Superman II, a 22 year old Kate Bosworth plays Lois Lane. Made all the more noticeable when the five foot five actress is playing opposite six foot three Brandon Routh.
Deleted Scene: The intended opening scene, of Superman surveying the remains of Krypton in his Kryptonian spacecraft, was completely cut out. It can be seen in its entirety here.
The final casting for the role came down to Brandon Routh and a then unknown Henry Cavill. Cavill was in fact cast in 2004 before McG was fired and Singer brought in. Cavill was later cast in the role by Zack Snyder in 2013's Man of Steel.
Jim Caviezel expressed great interest in the role of Superman but Singer refused to cast the then 36 year old actor, even though he had the right look and the age of a more mature Superman, simply because Singer thought he was "too famous" after the controversial The Passion of the Christ - ironic considering that Singer tried really hard to pass Superman off as a Christ figure and Caviezel had just played Jesus Christ himself.
During the initial fallout of the film's theatrical run Singer kept insisting in interviews that he would follow up with a more action packed sequel, he even likened his intended sequel to Star Trek II The Wrathof Khan repeatedly (specifically saying that now that he had the set up he would go "all Wrath of Khan on it.") But due to the polarizing audience response and a lot of debate over the film's box office the sequel ultimately got scrapped in favor of what eventually became the 2013 Man of Steel reboot.