When the 2001 series Cyborg 009 first aired on Toonami in summer 2003, various early-run episodes were initially broadcast in a less-edited format, and contained language that was later deemed too objectionable for the Y-7 rating placed on the series. Two such episodes that existed were episodes 3 and 4, "Assassin of Flash" and "At the End of the Battle".
In the first, the villain Cyborg 0010- states as part of his speech; "Truly, I'm your brother from HELL!". In the latter episode, Cyborg 002, in his rant about not trusting others, shouts "I don't even believe in God!". While the dub was notable for its liberties in dialogue (which increased through its run), these two lines ran closer to what was intended from the Japanese version.
After Cartoon Network's Standards and Practices Department realized such language slipped by the rating, the former episode had the objectionable word muted in its early rebroadcasts, before the line was later fully redubbed to be "I am your brother gone BAD!" for Sony Pictures Home Entertainment's DVD releases. In the case of episode 4, 002's line was redubbed to "I couldn't even trust my parents!".
Oddly enough, due to Sony lacking proper subtitles on their DVD releases and instead recycling the dub scripts for the episodes (in the form of "dubtitles"), which included added dialogue where there was silence and added jokes, the two original lines do appear intact. However, in the case of the original dub audio, it would appear to be lost, aside from any recordings that fans may have saved from the first Toonami broadcasts.
While minor forms of lost media in comparison to other material that went missing from the dub (most notably the God's War episodes), these changes were very remarked upon.
Another form of lost material for season 1 involves the opening to the episode "The Hero", which has a brief scene of 009, 003, and Dr. Gilmore conversing, before wondering what 002 is up to in New York. Message board posts of the episode on its original airing indicate that this scene was intact. However, on Sony Pictures' R4 DVD of episodes 1-26, this scene appears to have went missing.
In material that was mostly discarded before the show made it to air, there was the curious case of 009's voice actor being swapped out. Originally, Derek Stephen Prince (under the alias "David Umanksy") recorded at least a dozen episodes in the 009 role, before the higher-ups ordered him fired due to his voice sounding too shrill. The voice director Michael Sorich then cast Joshua Seth in the role, after Seth had initially planned to retire from dubbing due to the poor pay (Seth would retire later on, however). Episodes 5 and 9 were seemingly unable to be re-recorded in time for the Cartoon Network airings, with the existing episodes that Derek Stephen Prince had voiced in having been re-dubbed out of order. These are the two episodes in which Prince's line readings can still be heard, making for a jarring experience for new viewers.