Continuity mistake: When Alex, the writer, and the other two political people are sitting at the table near the end of the movie, not only does the amount of sauce change on the spaghetti, but the amount of spaghetti changes from shot to shot even after Alex has stopped munching on it. This isn't part of the director's ploy.
Visible crew/equipment: The shadow of the camera can be seen many times on Alex and Miss Weathers during the fight scene in the clinic.
Continuity mistake: When Frank first pours the wine for Alex he fills it all the way to the top. The shot changes and he is still pouring the wine however the level of the glass has dropped to half full and he fills it up again.
Chosen answer: The droogs didn't like how Alex was leading them, so he attacked them. It's never explained whether the plan was to set him up all along, but given that Din was ready with the bottle to smash him over the head, it seems like an opportunity to be rid of him came up and they took it.
Captain Defenestrator