Revealing mistake: When Sgt. Troy throws the grenade at the Gestapo agents barricaded behind the table, it is thrown wide right, yet the pyrotechnic explosion is dead center of the table barricade.
Is There in Truth No Beauty? - S3-E5
Other mistake: In the final scene, Kirk is still in the transporter room, but does not have on a visor when the ambassador transports out. Even if he did, humans can still go mad if wearing one and that's why Spock operates the transporter. Spock has his visor on, but then you see Kirk walk out of the transporter room without a visor and he is not going mad.
Revealing mistake: When Briggs disguises himself as Rogosh's defense attorney, the glasses he puts on very obviously have no lenses in them. (00:26:05)
The U.N.C.L.E. Samurai Affair - S1-E27
Revealing mistake: Mark's stunt double in the final fight scene has a very bad (and obvious) brown wig. Mark's hair, however, is blond. (00:44:00)
Batman Stands Pat (2) - S1-E14
Continuity mistake: Batman's plaster-covered costume gets an instant dry cleaning en route as he drives from the sculptor's studio to the batcave. (00:05:00)