The Sontaran's hands show a glove with 5 fingers - Sontarans only have three fingers.
Something like 20,000 years has passed between this story and The Time Warrior (the previous Sontaran story which was set in the 13th Century). It seems implausible that a race as advanced as the Sontarans are still using the same ships, wearing the same clothing, and appear not to be any more technologically advanced after such a long time.