Continuity mistake: In Willy's flashback when he speaks to Crawford for the denouement, his SPH-a900 flip phone and Flores' swap position compared to how the actual scene went. Just look at the position of the three buttons; the buttons of Beachum's faced him originally, they face Flores when he grabs it by mistake in the flashback. (01:37:55 - 01:41:55)

Continuity mistake: When Willy rings Crawford's doorbell, notice a white control panel below the CCTV screen. Hopkins then answers the door in a different shot, with the panel missing. The panel was always there during his earlier scene with Nunally, and it is still there for the rest of the scene, missing again only in a later zoom-in on the monitor as Crawford checks on the prosecutor. Probably those were later reshoots. (01:39:25)
Continuity mistake: In the end of the film where Willy and Ted stand together in Ted's house, Ted says to Willy "See, you can't touch me, ever". The shot goes to Willy and you can see his finger off the trigger, yet in the close-up on the trigger you can see that Willy's finger is inside the trigger-guard and he pulls it out. (01:46:15)
Continuity mistake: When Crawford sees Willy out after telling him to get the eff out, Hopkins turns towards the door, fully lit. He then peeks out of the door, now showing a more dramatic shadow on it. (01:47:50)
Continuity mistake: In the glimpse of the last trial, the bailiff says, "All rise," as Judge Pincus walks in, and people behind the prosecution bench take the instruction all too zealously as they do it twice - in different ways. Check out the guy with a jacket on his arm next to the woman in red - in separate shots. (01:48:20)
Chosen answer: Once Crawford (Anthony Hopkins) took his wife off life support, it resulted in her dying. Crawford was arrested for murder, not because of taking her off life support but because his shooting of her resulted in her death ultimately. Crawford was only tried (and acquitted) for attempted murder. Since this is a new charge, double jeopardy did not apply.
He did not materially pull the plug, though, did he? He went through the proper procedure, and it was within his rights to do so. Not to mention there would be issue preclusion, and the facts established in the previous trial couldn't be relitigated.
Sammo ★