Well, that particular episode aired tonight, and I can now confirm that the captions said “the inventor of the no-spill mug is out there” when Lisa actually says, “the inventor of the walkie-talkie is out there.” I can think of no earthly reason for the text to have been changed, but there you have it.
Changing dialog happens in animation sometimes just for the sake of getting it to look better if the action has been drawn before the voice has been recorded (usual with TV animation.)
So perhaps “walkie talkie” simply matched the picture better.