Black has the same vowel stress as planet. Pronunciation-wise, it's "blăk" and "plă-nət". The Rainbowface said "blă-" or "plă-", so it still could be either, depending on the consonant involved. Of course, I'm coming from a Californian accent point of view, but since Universal is here also, I think it's applicable.
If anyone has the seventh film with subtitles, it could resolve this. My copy's in VHS, unfortunately.