I've got 1000's of tracks in my collection but Amarok shows the total track count as 1 less than either Songbird (Linux) or MediaMonkey (Windows).

As Songbird and MediaMonkey agree I'm assuming that Amarok is wrong but I'd like to know one way or another. MediaMonkey can generate a report of all the tracks in the collection but Amarok does not have anything comparable.

Any suggestions how I might achieve this (other than manually checking)?

You can read the tracks out from the database.
I am not aware that there is something with a nice GUI built into Amarok.