Here's a good summary, from Tekton (which is a well-known conservative apologetics site):
http://www.tektonics.org/lp/markend.php.
Note that this doesn't necessarily affect its canonical status. E.g. it is virtually certain that the story of the adultress in John 8 was not in the original of John. However I would still consider it canonical.
With Mark it's more complex because there are two different added endings (well, three if you count the Freer Logion which sometimes appears in the longer ending), and they come in varying versions. The contents generally duplicate things present in other Gospels. So it's a bit hard to know just which to include. But since canonical really just means that the Church uses it, one might reasonably accept the traditional text, which is the longer ending. However evangelicals committed to the accuracy specifically of the original manuscripts probably shouldn't use anything beyond 16:8. I wouldn't generally cite anything beyond 16:8 either.