I am using glossary module in Moodle 1.9.9.
There seems to be no validation on range of date and time for restricting the entries rating. Presently the time range can be set to same time in 'from' and 'to' date-time boxes(which happen to be same by default.). Also we can set 'to' date-time lesser than 'from' date-time. Although anyone assigning these dates and time would be wise enough to put valid dates and time,there should be some validation rule checking this.
The same appears to be happening to mod_forum
Similarly user can select 'No Grade' in scale select menu while allowing rating of entries in glossary.This creates empty 'Rate' menu against each entry which cannot be used. There should be some validation rule for this too. Fixed (perhaps MDL-27471)
We would just need to put some addRule statements in mod/glossary/mod_form.php to check the date and time entered and scale selected.