Emanations - S1-E9
Factual error: To protect the warp core, Janeway instructs Paris to move away from the rings at Warp 7. Moments later (Janeway, Torres and Tuvok are still in the same position), Paris tells Janeway they are 0.6 light years away from the rings. Warp 7 is 656 times the speed of light. It would take about 8 hours to travel 0.6 light years at Warp 7.
Suggested correction: The warp scale, especially since it's fictional, has never been precisely defined.
While it's never been defined, certain aspects of warp speed drive and the length of a light year are accepted. Even if Warp 7 is double what is suggested in the mistake, it would still be 4 hours. The scene in question shows no lengthy travel at Warp 7.
Factual error: The event horizon of a quantum singularity (aka black hole) is not a physical barrier you can punch a hole through but a theoretical one, which can't be escaped from without faster then light travel.