The computer tells Geordi that Risa is "climate controlled for optimum tourist comfort." As Risa hosts multiple species this would be impossible. For example, Vulcans would consider the comfort zone for humans to be quite cold, while Andorians would find it too hot.
When it was revealed that someone had tampered with the isolinear chips, no one suggested either DNA testing or fingerprint testing to verify who had altered the chips. Geordi changed the chips without wearing any form of protection to cover his fingerprints or to prevent leaving DNA.
The goof item below may give away important plot points.
While being brainwashed by the Romulans, Geordi uses his phaser to shoot O'Brien in the chest, killing him. However, when the camera pans to show O'Brien lying dead, his uniform shows no signs of being hit with phaser fire. Although this is a simulation by the Romulans, it is unlikely that they would omit this particular detail.