Corrected entry: Duncan says that Connor disappeared "ten years ago to the day." That would make it 1990. But in the television series which this movie follows, Connor and Duncan fight together in the series premiere. That was in 1992.
Corrected entry: In the final battle between Duncan and Kell, they begin in a long hallway on what appears to be, but is not definitely, the ground floor. They repeatedly knock one another over edges and down steps. At one point they are fighting amongst pipes in what might be a sewer. Yet in the final battle scene, even though they have continually fallen down, they are on top of a building on a steel framework, and they are definitely higher than a great number of surrounding buildings.
Corrected entry: When Kell destroys the Sanctuary and kills all the immortals there, nothing out of the ordinary happens, besides the usual quickenings. Later Methos tells us that the Sanctuary was built on Holy Ground, where immortals can never fight. So Kell broke one of the fundamental rules, with no consequences.