Second Sight - S4-E7
Plot hole: Kimble enters the bar in the midst of a fight between photographer Howie and a man he tried to blackmail. Kimble comes in too late to hear what the scuffle is about, yet after breaking it up, he somehow knows all about the incriminating photo that sparked it. (00:06:00)
The Night of the Raven - S2-E3
Plot hole: Antoinette is making miniature clothes for the soon-to-be shrunken West, but when West drinks the antidote to make him normal-sized, he is wearing the same clothes which would have been shredded as he grew back to normal size.
The Assassin - S6-E8
Plot hole: There's no way Shelley Hack could clean up all that mess of blood and three dead assassins with only an hour or so before her dinner party.
Episode #5.2 - S5-E2
Plot hole: Collision between the two planes would have been prevented by TCAS (traffic collision avoidance system) computer systems installed on both planes. The TCAS systems automatically coordinate with each other and issue a TA (Traffic Advisory) with an audible "TRAFFIC, TRAFFIC", then if on a course that could result in a collision or near miss, issue an RA (Resolution Advisory) to their respective flight crews. Typically one plane's flight crew is audibly ordered to "DESCEND, DESCEND" by its' TCAS and the other plane will be instructed to "CLIMB, CLIMB" by its' TCAS. The flight crew is required to follow their TCAS instructions over the air traffic controller's. All commercial airliners are required to have a functioning TCAS computer. These systems were obviously not under control of the terrorists, they were conveniently ignored in the plot. (00:03:20 - 00:06:47)
Honor Code - S6-E7
Plot hole: In the previous episode, when Jimmy offers to apologise to everyone about stealing money to pay back gambling debts, Eugene tells him not to, since if the other firm members found out they'd be obligated to report the theft, which could endanger the firm. This episode, Eugene justifies reporting Jimmy to the bar for saving the boy's life against the client's orders by shouting about Jimmy's gambling theft in front of all the firm members whom he previously said he didn't want to know about it.
Plot hole: The bad guy somehow knows what is going to happen (via the sketches) even though the events haven't happened yet, like knowing Mrs Peel was going to show up at Pool's mansion in that catsuit and hat, and that the scenes were going to play out like the sketches.