Los Angeles - SNA curfew?

I'm booked on tomorrow's UA263, an ORD to SNA flight with scheduled arrival at 22:46.

I just remembered the 11pm curfew at SNA.

What happens if the flight arrives after 11pm, and how likely is this to happen?

From the SNA website:

The County’s General Aviation Noise Ordinance (“GANO”) prohibits commercial departures between 22:00 and 07:00 (08:00 on Sundays) and commercial arrivals between 23:00 and 07:00 (08:00 on Sundays). The Airport Director or his designee may authorize a departure or arrival outside of the commercial operations hours for an emergency, mechanical, air traffic control or weather delay, which is substantially beyond the control of the air carrier. All curfew exemption requests are reviewed by JWA and must receive express approval in advance of the specific arrival or departure. The table below lists each commercial operation during curfew hours for the most recent month.

http://www.ocair.com/reportspublications/AccessNoise/curfewoperations/2012-03.aspx
http://www.ocair.com/reportspublications/AccessNoise/curfewoperations/2012-02.aspx
http://www.ocair.com/reportspublications/AccessNoise/curfewoperations/2012-01.aspx

From those tables, I'd say that you don't have a thing to worry about as it looks like when arrivals occur after the 2300 curfew they're routinely approved.