Continuity mistake: The background of the cell does not jibe with the positions of Kirk and Cloud William as they fight - where Kirk and Cloud William should have either the cell's bars or the exposed brick wall behind them, there are shots of the opposite wall behind them instead, which is a plastered rock facing.
Factual error: In the opening sequence, Spock identifies the alien ship as possessing "ion propulsion" which he says is "unique technology." Scotty is similarly impressed and says, "They could teach us a thing or two!" Kirk later comments that "Advanced ion propulsion is beyond even our capabilities." However, even back in the 1960s, ion propulsion was physically feasible, while Warp propulsion was complete fantasy. Ion propulsion of any kind could never even reach lightspeed and would be incredibly primitive compared to Warp technology. In fact, we in the 21st Century have already developed ion propulsion, but it will probably take many hundreds or thousands of years to develop anything even close to Warp technology.
Add timeCharles Austin Miller