Dolim's lieutenant reports there are seven humans on Degra's ship. However, there were only six.
When T'Pol is recording her acting Captains log she states that the year is 2152. However, previously when Archer recorded his logs he stated that the year is 2154. They have not gone back in time so therefore, it should not be 2 years earlier than the last time a log was recorded.
The ability to travel great distances more quickly has been an overriding preoccupation of Earth's ship development, and Enterprise's crew. Adopting the Xindi's ability to open vortexes would be a huge boon, yet Archer and the others clearly learned nothing about the technology from their time using it on Degra's ship, and Earth must have made no attempt to learn more during a continued relationship with the Xindi, because this technology never became part of the Federation repertoire (much to the chagrin of Voyager's crew, certainly).
It is unclear why Enterprise did not contact Earth to warn them of the approaching Reptilian craft escorting the weapon, so that Earth could scramble fighting vessels--including those of its allied Vulcans--to help defend Archer aboard Degra's ship. Even without warning, though, Earth should have picked up the incoming alien vessels and taken defensive actions.
In her log entry near the end, T'Pol incorrectly states the year as 2152. The last few episodes have established that the year is 2154.