During Number Six's exercise routine, he can be seen using a high bar, swing rope and punch bag. However, on the reverse shot of him using the punch bag, the high bar has disappeared.
Number One usually rings on the big red phone, or the regular red phone, but in this episode he calls on the yellow phone.
The computer states that Number Six takes his daily morning stroll at about 6:30 am, yet when the activities supervisor sees Number Two with a activities prognosis report on Number Six, she states the time as being 10:19 and that #6 should be taking his daily stroll.
Number 6 takes the watch-maker's daughter to go see her father, but when they enter his watch-maker's shop, the sign hanging on a pole out front says Cafe.
In the scene in which Number Six visits Number Two to warn him of the assassination plot, Number Two's line "...it's the little watchmaker that concerns you", is dubbed over the original dialogue, and Number 2's lips can be seen moving at one point when there is no audio.
During the brief footage of the chess game, a Welsh flag (red dragon on green and white background) can be seen on the Village flagpole.
When Number One Hundred switches Number Six's watch, you can see the hour and minute hands are not in the same position; surely Number Six would notice the time on his watch was now different, even if it had stopped.