Factual error: New twenty dollar bills are visible in the tip jar, despite the fact that the Vulcans crashed on Earth in the 1950s.

Continuity: When Reed instructs Archer how to disarm the second arming mechanism of the mine, he tells him to turn the first component clockwise, but then Archer is shown turning it counter-clockwise. Then Reed tells him to turn the rest of the components counter-clockwise, but afterwards he must reverse the last component to keep the mine from rearming, which means turning it clockwise. But when Archer reverses the last component, he turns it counter-clockwise.

Continuity: T'Pol says she has never been camping, but she went in "Strange New World."

Continuity: Archer says he doesn't remember T'Pol being attacked in "Fusion." But in that episode, he lured T'Pol's attacker into his cabin, got into a fight, and threatened him with a phase pistol because he knew the guy assaulted T'Pol.

Continuity: Admiral Forrest says this is the "first time" the Vulcans have asked Earth for help. But they asked Earth for help in "Fallen Hero."

Other: Two Borg are discovered North of the Arctic Circle. One is covered in ice, the other encased in ice. Carbon dating shows the wreckage to be over 100 years old (to tie it in with Star Trek:First Contact). The Borg are inactive and unable to repair themselves until they are "defrosted". The temperature above the Arctic Circle doesn't usually drop below -100°F. The Borg have been shown to work very well in the vacuum of space which is 3-4K (roughly -454°F). If they can survive that, even being frozen in a solid block of ice would not slow them down. The nanites have to be in their "blood" and operate at the cellular level. That cannot be damaged by re-entry and the crash. [This is one of those entries that keeps being corrected and recorrected - I'll leave it up to people to make up their own minds.]