What version are you running?
RB 1.7.2 (yes I know it's outdated but we haven't updated yet and I didn't see items in the release notes that looked related to this issue.)
The problem occurs when we create a review request without a diff but attache the diff later.
You can see this here http://rb.freedroid.org/r/1878/ in the second change of the RR.
RB offers to "Show changes" between the current diff and the previous diff (I assume code says "current diff -1" but since the diff was attached afterwards an is the first diff, the previous diff is diff "0".
RB now tries to show the changes between diff0 and diff1 which fails obviously.
http://rb.freedroid.org/r/1878/diff/0-1/
It's only a minor issue but probably also easy to fix.
Regards, Matthias
