In the 2002 TV film "It's a Very Merry Muppet Christmas Movie", there's a part where an angel shows Kermit an alrernate reality where he was never born. For whatever reason, the editors didn't really think about it, and continued to use footage with the twin towers still standing for this scene; however, they aren't there in his original universe. Therefore, something that Kermit did in his life, did in fact cause 9/11 in Muppet lore.
𝓜𝔂 𝓭𝓮𝓪𝓻𝓮𝓼𝓽 𝓫𝓻𝓸𝓽𝓱𝓮𝓻, 𝓽𝓸𝓭𝓪𝔂 𝓶𝓪𝓻𝓴𝓼 𝓽𝓱𝓮 8𝓽𝓱 𝔂𝓮𝓪𝓻 𝔀𝓮 𝓱𝓪𝓿𝓮 𝓱𝓪𝓭 𝔀𝓲𝓽𝓱𝓸𝓾𝓽 𝓿𝓪𝓻𝓲𝓮𝓽𝔂. 𝓦𝓮 𝓶𝓪𝔂 𝓷𝓸𝓽 𝓫𝓮 𝓪𝓫𝓵𝓮 𝓽𝓸 𝓮𝓷𝓭𝓾𝓻𝓮. 𝓟𝓵𝓮𝓪𝓼𝓮 𝓹𝓻𝓪𝔂 𝓯𝓸𝓻 𝓸𝓾𝓻 𝓼𝓪𝓵𝓿𝓪𝓽𝓲𝓸𝓷. .