The big one is the complete aversion of (to?) Girl on Girl Is Hot. You see Cathy and Michael kissing, and Michael and Lina kissing, but never Cathy and Lina. Did one or both of the actresses turn down the idea, or was it never suggested?
Alternative Character Interpretation: Michael is supposed to be the luckiest bastard on Earth as Cathy and Lina are apparently competing for him, rather than Michael and Cathy sharing Lina.