In the trial, Valiant is shown in the first shot of the courtroom sitting in the second bench on the right, behind Ian and before Robert, but when he goes up to testify, he is walking all the way up from somewhere near the back. After this, he is always in the original spot.
In the beginning, Valliant's letter is shown as being short, completely written on one side of the parchment. However, at the end when it is shown, the last words being read are all on what is obviously one side of parchment while the rest must be on the other, making it a longer message than previously seen (also, the word "all" which is read is missing).
During the first shot through the trial, four people sit beside Robert, three beside Valiant. When Robert stands up to defend Duncan, the person nearest to him (shown in the side of the shot) is too far away for there to be more than three people on the same bench.
Valiant runs to the rail just before the scream from below sounds, but in his flashback he is shown (and describes himself as) running over after it sounds.