The Man Behind the Curtain - S3-E20
Corrected entry: When Sawyer was playing the tape to the group showing where Juliet was still working for the others; she and Jack walked up and she told them to turn the tape over and play it. On the other side it had her instructions and what they were planning to do in the next two days. She said she told Jack what the others were forcing her to do and what they had planed and when. However, earlier Richard was asking Ben if he wanted him to deliver the tape with the new instructions for Juliet and Ben was telling him he already did the instructions and was fixing to ask Tom where it was when Locke interrupted him by walking into camp carrying his dead father. Plus there was no recorder there for Ben to tape instructions and even if he did, there was no way Juliet could have known what was on the opposite side of the tape for Locke had took it and gave it to Sawyer.
Correction: I don't believe there's a mistake here. John Locke saw Ben put the recorder in the drawer. That's how he knew what to steal and from where. For Juliet it was just the normal routine. Whenever she got the recorder back, instructions would be on the other side of the tape. It is somewhat strange though that Juliet's side is playing instead of the side last recorded while John Locke didn't mention the impending assault on the camp to Sawyer.