Well the other three did happen, at the end, you ll see a little shrine with the ooze canister and the shredder helmet, and the time scepter from part III. Shredder is no where seen in this one, they could of at least added Krang for Fucks sake! Oh well.... we ll have to wait for Krang.
hmm as an original fan of the comics where Shredder was only in maybe 5 issues this sounds almost good. the real question though did it have any version of Vanilla Ice's Turtle Rap? "Go ninja go ninja go!"