There are a couple of bits that were trimmed (also on the Canadian premiere as well). One is right at the very beginning of the Last of the Time Lords, as the planet shuts down when Saxon took control. It may not seem like much, but it does make a reference to Sol 3 which is used again in the Christmas special. Another part is a bit of a musical sequence with the Master, lording his presence over all his captives. It's a brilliant scene, in my opinion, because it gives us a glimpse into how life on the Valiant has been over the past year. Lucy's attitude around her husband has certainly changed (see the bruising), and it makes the ending a bit more understandable. Another important scene that I can think of (as these are just off the top of my head) is between Francine (Martha's mum) and the Master, just before he is shot by Lucy.