At the beginning of the episode, Kawalski sees a surface ship on the radar, which is the 17th Century ship. But, radar works by radio waves bouncing off metallic objects. The ship is made of wood so would never have registered on radar.
At about 7:20 the man at the console blinks even though he is supposed to be in suspended animation.
Richard Basehart forgets to remove his modern wristwatch when he plays Capt. Seamus O'Hara Nelson.
When Adm. Nelson covers Chief Sharkey in foam, he calls him "Chip" instead of "Chief". Chip Morton is the ship's XO.