Deliberate mistake: The dying Vantika hides his consciousness away in a portion of Dr. Bashir's mind. At one point, "Bashir" (heavily cloaked in clothing and shadows) comes up behind Quark and makes sure his demands are clear. At this point, it should still be unclear just how Vantika is still "alive", and whose body he is using. However, when he shoves Quark away, for a fraction of a second, Bashir's face can be seen under his hood. They were true to plot in using the right actor (though he shouldn't have been seen), it is possible some might have spied the secret earlier than the show meant to reveal it.
Star Trek: Deep Space Nine (1993)
1 deliberate mistake in The Passenger
Body Parts - S4-E25
Visible crew/equipment: During a pan-across of Quark's bar after it has been emptied out, the shadow of the camera is visible for a moment in the bottom right corner of the screen. (00:40:35)
What You Leave Behind (2) - S7-E26
Quark: The more things change, the more they stay the same.
If Wishes were Horses - S1-E16
Trivia: Buck Bokai, a baseball player from the 21st Century, who becomes "real" in this episode, broke Joe DiMaggio's consecutive hitting streak in 2026. While he's not physically seen or referred to by name, this fact is mentioned in the 'Star Trek: The Next Generation' episode "The Big Goodbye."
Emissary (1) - S1-E1
Question: Did Nana Visitor's hairstyle change from her first appearance in the episode to the next scene when they were going down the stairs?