Continuity mistake: As Geordi talks to Ms. Rogers, Riker is walking in the background by some containers and a crewman in blue. After a cut to Ms. Rogers, Riker is suddenly alone with a data pad.
Descent (1) - S6-E26
Revealing mistake: In the hand-to-hand with the Borg soldier, Data's stunt double is easily identifiable.
Audio problem: We hear Reva's female member of his choir say "I have been expecting you", but her mouth doesn't move.
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.
Continuity mistake: As Worf goes to enter the portal to the Enterprise carrying Data, his right hand is free, and his left is holding Data's left hand. Appearing on the bridge, Worf's left hand is on Data's leg, his right hand on Data's wrist.
Where Silence Has Lease - S2-E2
Visible crew/equipment: As Picard approaches Data's position, the boom mic is reflected on the panel behind him.
Continuity mistake: When Wesley Crusher and his school chum accidentally hit Picard with a snowball from the holodeck doorway, it makes a huge wet spot on the captain's left shoulder. However, when Picard tells them "Don't let it happen again," as he turns to walk away, the wet spot is now suddenly dry. (00:36:00)
Devil's Due - S4-E13
Continuity mistake: In Picard's quarters, Ardra appears as Troi. After reappearing as herself, she puts her hands on her hips. After the angle change, she repeats the motion.
Continuity mistake: When talking to Ral, Riker takes a sip of his drink, sets the glass down, and clasps his hands. A second later, he repeats clasping his hands.
Factual error: When the starboard nacelle causes the ship to spin, the view of the stars on the main screen on the bridge should move toward the right side of the screen, rather than standing still.
We'll Always Have Paris - S1-E24
Continuity mistake: The red towel Picard holds goes from draped over the front of the arm rest, to over his hand between angles.
Continuity mistake: When the Enterprise activates the deflector dish, there are four points emitting beams. However, there are five beams emitting after the angle changes.
Other mistake: After the signal change to a continuous output, the Crystalline Entity vibrates. As it does, look at the background stars. They also vibrate in time with the Entity, although the signal is focused on Entity alone.
Continuity mistake: When Picard looks down the mountain to look at the town he has a straw hat in his left hand, next shot it's gone.
Continuity mistake: In Dixon Hill's outer office, Gloria's right arm goes from being up to by her side and back between camera cuts.
The Best of Both Worlds (1) - S3-E26
Other mistake: When O'Brien activates the transporter, only the very bottom indicator lights come on, even as he moves his hand up. Usually the indicator lights match the movement of the hand.
Visible crew/equipment: As Kolrami talks to Picard from beside the aquarium, you can see the studio light panels reflected on the glass.
Answer: He brought the Borg to the Alpha Quadrant and showed them that it was full of worlds waiting to be assimilated. Guinan's homeworld was their first stop, and they assimilated everyone and took over the planet, leaving The Survivors of her race without a home. Q is ultimately responsible for that.
Captain Defenestrator
By the time Q takes the Enterprise to meet the Borg, Guinan already knew who they were and they had already destroyed her world. Therefore the above answer can not be right. I believe Guinan is much more than she appears, and her people have had encounters with the Q in the past. It is these interactions, that obviously were not pleasant, that fuels her distrust.
oldbaldyone
That's what the above answer is saying. Q brought the Borg to the Alpha Quadrant (not Earth) and the Borg destroyed Guinan's home world in the late 2200's, which is why she hates Q. Although she met Q in 2160 and they both saw each other as enemies right away.
Bishop73