Here's information on getting a replacement for discs from "Superman":
Statement from Warner Home Video, November 29, 2006
To Purchasers of the “Superman Ultimate Collector’s Edition”, “Superman: The Movie Four Disc Special Edition” and “The Christopher Reeve Superman Collection” – Region One Only: Bonus content was inadvertently omitted from some of the "Superman III Deluxe Editions" contained within the 14-disc "Superman Ultimate Collector's Edition."
Also, disc one of the "Superman: The Movie Four Disc Special Edition", “The Christopher Reeve Collection” and the “Superman Ultimate Collector’s Edition” inadvertently did not include the original 1978 Theatrical Dolby Digital 2.0 mix, although the disc does contain the Dolby Surround 5.1 mix. Please note that these discs are not defective; we have received no complaints regarding the playability of these discs.
Warner Home Video has taken immediate steps to correct these unintentional errors. Replacement discs can be obtained, at no cost to the consumer, by calling: 800-553-6937. Warner Home Video will provide consumers with a pre-paid, pre-addressed envelope for sending the discs they are returning to Warner Home Video. Upon receipt of the purchased discs, Warner Home Video will send replacement discs as soon as they become available, currently anticipated in mid-December 2006.
Only Region 1 discs from the “Superman III Deluxe Edition” contained within the “Superman Ultimate Collector's Edition” and disc one of “Superman: The Movie Four Disc Special Edition,” “The Christopher Reeve Superman Collection” and the “Superman Ultimate Collector's Edition” are eligible to participate in this exchange program. Warner Home Video will honor all requests for replacement discs that comply with the exchange program requirements.