Star Trek: The Next Generation (1987)

Deja Q - S3-E13

Continuity mistake: As Q approaches Picard and Riker's position while playing a trumpet, both of Q's hands are on the horn. A second later, his left hand is down by his side. Then, after he makes cigars appear in Picard and Riker's mouths, his left hand is extended as he says the first part of his lines. A second later, both hands are on his horn.

Deja Q - S3-E13

Revealing mistake: On the bridge, as Q snaps his fingers to pop cigars into Riker and Picard's mouths, his hand and their positions change by a few inches. This shows the filming stopped to put the cigars into their mouths.

Deja Q - S3-E13

Continuity mistake: On the bridge, as Picard addresses him, Q turns his head to face him. After the angle change, he does it again without having turned it away.