Leaving the referee aside for the moment (and worry ye not, there will be a lot on Mr. Murray to come later) what about the game as a whole?
Losing is one thing we've become too familiar with in recent derbies but was this, as some seem to have suggested, some form of improvement?
The short answer to that is 'no,not really' but the long answer needs to look at the options available.
It's certainly the case that the three-man central defence worked well up to a point - Weir was less exposed initially and for most of the first-half Celtic's threats were minimal - but after the red card for Whittaker it became all too apparent that our plan was a little vulnerable.
Simply put: when your approach to a game is taut, so lacking in any wriggle-room, then the slightest blow leads to problems and nullifies its effectiveness.
Walter's first and second choice forwards were missing, and Rangers were denied the services of a handful of others who would certainly have started or made for significant replacements.
So, once again, it was about containment; absorbing pressure and hoping to find a goal on the break or through a set-piece opportunity.
Once Rangers were reduced to ten it didn't change but simply became more difficult and asked more (too much) of those trusted with the offensive responsibilities.
You can go on and on about the ref (and some will) but the fact remains that the (on-the-night) rather shaky Celtic central defensive partnership and erratic Polish goalkeeper weren't tested adequately and a list of Rangers shots on goal would fit on a first-class stamp.
At the other end, Celtic's full-backs weren't initially so much of a concern as attacking options, and Foster coped admirably with Izaguirre. But the one time he allowed the full-back to get in a decent cross lead to the sort of defensive muddle all too regularly witnessed this season. The ball is allowed to go through players, there's an excellent and all-too-costly block from Sasa and the resulting follow-up hits the pitch, bounces over the almost prostrate McGregor and finds Bougherra recovering from Papac concern and swinging at it with what appeared to be the wrong foot. Another howler, if rather fortuitous.
Rangers never looked like finding an equaliser and some will again wonder why another attacker wasn't brought on earlier - the margin of defeat matters not in a cup game - but so much of what happened last night merely illustrated the lack of firepower and troops at the disposal of General Smith. Hamstrung by injury - literally in the case of Jelavic - and rendered impotent by the setback of the man disadvantage.
There's also the very simple problem of not having the men with appropriate skills to allow for different game-plans to be explored or executed.
To select an example; Mo Edu is an often-effective, largely destructive player, whom one would be comfortable having as the fourth or perhaps third member of your midfield corps but not as the second-in-command, expected to assume that level of creative as well as positional responsibility and discipline. A midfield where Davis is the one man with flair or ability to pass the ball simply isn't going to cut it in the absence of quality or experienced reinforcements.
In terms of the remaining Glasgow derbies this season, this would have ranked third in the list of importance. The next game, the League Cup Final, will again be difficult if injuries don't clear up but it must also witness a change in approach.
Plan A and Plan Aa have not worked, although there were early signs that the latter has potential if the offensive cast can be comprised of more able men. If Naismith, Jelavic and Weiss are all fit then all must play. This need not mean a real change in nominal formation but it certainly does signal a change in intent - there has to be a constant and determined attempt to hurt Celtic at the heart of their defence.
In wider terms, the SPL title is still very much a prospect and last night's exit will allow one or more games to be accommodated on weekends reserved for cup football. But what last night showed us is that this squad is now stretched toward and indeed almost beyond the limit. We can only hope that the dark arts on show will bring the squad closer together and allow them to focus on the importance of ending the season with the major silverware.