OK so I've just been rewatching R1 and it occurs to me that Lelouch: obviously a very intelligent chap, comes up with the most lazy excuse for why Shirley doesn't remember who he is after he Geasses her. He says that she's angry at him after a fight and is pretending not to remember who he is.
I admire him for not using her father's death as a cheap excuse for his own gain, but seriously that's such an easy excuse! Just say that she's all trauma'd up by her dad's death and can't remember who he is. It's not like they'd force her into therapy and thereby invite attention from the Brittanians.
In the end it doesn't matter cos nobody notices, but don't you think it makes him look less intelligent than he is?
And to make the thread less preposterously specific. I invite mass discussion over any other tactical fails of Lelouch's. For example consistently not predicting the arrival of the Lancelot in every battle he ever has to deal with.