Continuity mistake: When Blackthorne tries to open the door in order to leave the room he woke up in, his hand tears the paper wall. The damage to the paper then changes between shots. (00:11:20)
Revealing mistake: Right after Father Alvito hands Blackthorne the Portuguese-Japanese dictionary, the Jesuit priests leave Blackthorne and his entourage to continue their journey onto the port of Nimazu. You can see the orange-robed clerics walk along a track that was obviously used by wheeled vehicles. You can see grass growing in the middle of the dirt road and none in the grooves. But in an earlier scene Father Alvito stated that only the Emperor was allowed to drive in a wheeled cart which he only did it on rare occasions for ceremonial purposes and for short distances as this would otherwise damage the roads (as the grooves testify). (01:28:00 - 01:30:10)
Visible crew/equipment: In the opening scene you see an old ship in the water, if you look closely you can also see the shadow of the helicopter that is filming the scene.
Factual error: When they first meet, Rodrigues tells Blackthorne that aboard his ship there is plenty of food and grog. The problem is that grog was not "invented" until 1740, when it was introduced into the British Navy by Admiral Edward Vernon, who was nicknamed "Old Grog" because of his habit of wearing a grogram coat.
Factual error: When Rodriguez is in his cabin with Blackthorne after having been saved by Yabu, he tells Blackthorne, "There's a bottle of grog over there." Grog was only invented, as it were, in 1740 by British Vice Admiral Edward Vernon, whose nickname was "Old Grog" because he wore a cloak of grogram cloth.
Factual error: Throughout the show, flintlock firearms are used. The show is set in 1600, and the flintlock was not invented until about 1630.
Other mistake: After Lord Buntaro's archery demonstration, Blackthorne comes over to the post which now bears the three arrows shot by the Japanese. In the paper wall behind him a hole can be seen, which is to be the spot through which the arrows have come. but the arrows and the hole do not make one straight line, which would have to be the case if the missiles were to really have arrived from there.