Goofs

The amount of liquid in Phlox's glass changes between shots.

When Archer and his team go in search of the Gorn they are seen climbing up a Jeffries tube to his last known location using a triangular ladder (which is actually a common outdoors antenna mast). In the previous episode a crew member was seen climbing up the same Jeffries tube using steps on the side with no ladder.

Both T'Pol and Phlox are shown transporting from the Defiant to the Avenger while the ships are traveling at high warp. As of the 23rd century transporting between ships traveling at warp speed wasn't possible, even at warp one. Technology had advanced enough for it to be possible by the late 24th century, but even then it was considered extremely risky. The Best of Both Worlds (1990) is one of the very few instances of transporters being used at warp speed, for it to be possible both ships had to be traveling at the exact same warp velocity, and even then it was still extremely dangerous as mentioned in The Emissary (1989), which was the other rare instance of a transporter being used at warp speed.

In his speech to the assembled crew, Archer says that the Terran Empire has existed "for centuries". This is impossible. He is speaking in 2155, and Terrans first learned that there were other planets out there to conquer in 2063. This gives them fewer than 92 years in which to build a trans-planetary empire. In fact the empire existed long before the discovery of other species. The Terran Empire flag is seen being planted on the moon. There's no evidence in the Star Trek universe to suggest that the Terran Empire was formed because they realised there were aliens. Instead this episode (including the speech in question) indicates that the empire existed long before they knew there were aliens. Terrans were already collectively violent and xenophobic when the Vulcans arrived.

When Archer is speaking with Admiral Gardner, the admiral moves around the room he's in, and the camera pans and moves along with him. This is the only instance in the entire series in which a bridge camera pans, and it's likely a mistake.

When the Defiant rendezvous with the Empire fleet the are in a battle with Vulcan, Tellarite and Andorian rebel ships. However, on the bridge of the Admirals ship there is an Andorian at the helm and can be seen in a couple of other scenes after.

After commandeering the Defiant, Archer and company inexplicably adopt the uniforms of the original crew.

The USS Defiant fires blue photon torpedoes, but in Star Trek (1966), photon torpedoes were originally white (and in the updated HD version, are red). Since the USS Defiant is a contemporary for the USS Enterprise NCC-1701, it should be firing similarly contemporary-colored photon torpedoes.