since the instance is being used to do an insert into the database, not an update

Do you mean that in the dev environment you're doing an insert, but on the test and prod environments you're doing updates? I'm a little unclear on the concept. Shouldn't the code handle both scenarios?

I would not worry so much about the warning, it's doing its job: telling you something odd is happening. I would instead concentrate on the program logic and trace back to where $HASH{key} is being set, or more importantly, why it's not. Don't shoot the messenger.

And set my mind at ease, tell you you don't really have a hash variable in your code named HASH? There are surely better names that would do?