Shared with you
This episode confirms that the transporter was invented much earlier in the Star Trek timeline than was previously believed. In his book "The Star Trek Chronology: The History of the Future", Michael Okuda speculated that the transporter was invented shortly before the events of Star Trek (1966). This was suggested by a line from Star Trek: The Next Generation (1987) (which took place a century later) which stated that transporters had been safely used for personal transport for about 100 years. However, this line could also have referred to a deadly transporter accident in Star Trek: The Motion Picture (1979), indicating that since then, no major incidents had taken place, and the technology was considered safe. The later episode Daedalus (2005) placed the invention of the transporter somewhere in the early 22nd century.
Hoshi's insult to T'Pol, "Ponfo mirann", loosely translates to "Go to hell".
Three of the prominent Starfleet officers are called Admiral Forrest (Vaughn Armstrong), Admiral Leonard (Jim Beaver) and Commander Williams (Jim Fitzpatrick). These names are an homage to the three lead actors from Star Trek (1966): DeForest Kelley, Leonard Nimoy and William Shatner. One of the Vulcans from the High Command is called "Tos", which is a reference to TOS, as The Original Series is often called.
Ensign Mayweather, when discussing the transporters, says "from what I'm told, [the Captain] wouldn't even put his dog through this thing." The dog in question is Captain Archer's beagle, Porthos. Years later, in the film reboot Star Trek (2009), a surly Montgomery Scott describes his ongoing punishment by Starfleet as a consequence of attempting to prove a transporter theory correct by transporting "Admiral Archer's prize beagle," who was transported and never rematerialized.
Up to this series, the pilot of each Star Trek series after the first included a cameo of a character from the previous one. However, because "Enterprise" takes place 100 years before Star Trek (1966), the cameo was not of a series character, but of Zefram Cochrane (James Cromwell), who appeared in Star Trek: First Contact (1996) and in Metamorphosis (1967) portrayed by Glenn Corbett.
Vaughn Armstrong, a longtime Trek actor, appears here as a human for the first time, bringing his total Trek appearances to eleven - as 9 different characters, and 7 different species (human, Cardassian, Klingon, Romulan, Borg, Vidiian, Hirogen).