6. Inconsistent Designs
The USS Defiant that debuted during DS9's third season was a 37-inch physical model. However, by the fourth season, a CGI version was commissioned to appear in the show's revamped opening titles and in later episodes where the ship was expected to execute maneuvers that were difficult or impossible to achieve with traditional model photography.
This computer-generated model was among the first "hero ships" in the Star Trek franchise to be rendered digitally and the limitations of the medium meant that the Defiant that appeared in the new intro was a slightly off-model version. While it appears for only a few seconds beginning in the fourth season opener, "The Way of the Warrior", the opening titles version of the Defiant has a noticeably squat configuration and smaller nose section than the physical model that appeared in earlier episodes.
Additional CG models of the ship appeared in future episodes with varying degrees of accuracy to the physical studio model, including a digital Defiant rendered by ILM in Star Trek: First Contact and another created by Digital Muse that appeared in both DS9 and Voyager, identifiable by its skinnier, boxier deflector dish and less angular warp cowlings.