Recently we reviewed a pull request and didn't think anything of a binary file that was modified at one commit, then "unmodified" at another commit in the branch.
After the branch was merged, we found that the binary file had been corrupted. This was introduced in the second commit. The pull request had said "File contents unchanged." so reviewers expected no corruption, but in fact, the file had been changed.
If you need the URLs to our pull request, don't hesitate to contact me.
An image of what the PR displays is below: