When The Bough Breaks - S1-E17
Visible crew/equipment: After finishing his talk with Harry, Riker continues to walk into the Turbolift. A leg from a light stand can be seen in the lower right hand corner as Riker walks into the lift. [Not visible in the remastered Blu-ray version]. (00:00:45)
When The Bough Breaks - S1-E17
Audio problem: Riker's lips don't match what he is saying when we hear Riker's statement of being surprised when Tasha hasn't heard of the stories of Aldea.
When The Bough Breaks - S1-E17
Continuity mistake: When Wesley is being introduced to the Companion, the camera zooms in to see the entire console up on the full screen with NO hands on it, but when it cuts to a side view, Radue's wife's hands are on the console.
When The Bough Breaks - S1-E17
Visible crew/equipment: When Data and Geordi come up to address Picard, there are two lines of tape on the floor for positions.
Answer: Yes. The doors to the holodecks can be locked when in use by anyone aboard the Enterprise so they couldn't be disturbed. However, high ranking officers like Captain Picard could override the doors as it's seen that overrides are in use even for the crews quarters. Even Barclay, when he's indulging in one of his fantasies could have the doors to the holodeck unlocked by an override code.