Check Syntax alpha-renaming does not work with `define-struct'.

The alpha-renaming feature of Check Syntax may miss some
  identifiers. Check which identifiers will be renamed by moving the
  mouse cursor over the *binding* occurrance of the variable you want
  to rename. The arrows point to all known bound occurrances, which
  are the identifiers that are renamed by alpha renaming.

After breaking a long interaction several times, one of the breaks
  may carry over to the next interaction.

The yellow execute warning in the interactions window does not go away
  if the user undoes all changes to the defintions window.

Backup files don't preserve file permissions.

For a more complete listing of known bugs, see our
<a href="http://www.cs.rice.edu/CS/PLT/Bugs/query-pr.shtml">
online bug report database</a>