The ending
[spoiler]Just a thought about the ending scene. Judge Wargrave shoots himself in the neck from below of his head. Because of this, it wouldn't necessarily seem believable that U.N. Owen would have shot him. The Judge wanted to make impression that him and Owen were having glass of wine in the table, and Owen shot him across the table. More believable would have been a shot in the forehead for example.
[spoiler]This last thing could have endangered Judge Wargrave's whole master plan - to create perfect murder mystery, stay unknown and be remembered.