The Chuck flashback, presumably takes place before the events of 'Uno'. It shows Jimmy wearing Marco's pinky ring, sometime before May 2002. Actually, It was given to him months later, in 'Marco', after Marco's death, in July 2002.
In the post-credits "Farewell and Thank You" motion graphic, the final outfit is a "BCDC" (Bernalillo County Detention Center) shirt. However, Jimmy McGill is serving his time at ADX Montrose, which is a fictionalized version of ADX Florence (a federal prison).
Federal prisoners are always transported via JPATS (Justice Prisoner and Alien Transportation System), otherwise known as Con Air. On rare occasions that commercial airlines are used, there are always a minimum of two Deputy Marshal's escorting the prisoner, never only one. And the rearmost row of seats are used to prevent them being assaulted from behind.
Prison sentences in federal court are given in months not in years.
When Saul is speculating about time travel and regret, Walt tells him that time travel violates the second law of thermodynamics. The second law of thermodynamics only deals with energy and entropy in an isolated system.
After grabbing the H.G. Wells' book (The Time Machine) Chuck (Michael McKean) fails to grab the handle of the light on the first try.
Jimmy refers to Steve Jobs in the past tense. Jobs was still alive in December 2010 when this scene takes place - he died the following October.