71 - Borg

I still don't buy the notion that the unseen enemy in The Neutral Zone episode of TNG was The Borg - at least, the Borg as we they emerged in the Season 2 episode Q-Who.

There was a notion that a species of aliens, with a hive mind, but insectoid in nature were to be those behind it; they were due to be introduced in the first couple of episodes of season 2. But a combination of the writers' strike (why there a fewer episodes in that season), and an inability to come up with a design for the creatures that they could make on budget meant these aliens were scrapped. 

But the notion of aliens with a hive mind stayed in the producers' minds and this is what eventually became The Borg.

So... why could these Neutral Zone aliens not be The Borg?

Well... cast your mind back to exactly how the Enterprise first encounter the Borg... Q flings the Enterprise across the galaxy, to an area no humans have ever gone. Q makes it quite clear that this encounter with the Borg has drawn humanity to their attention and they are on their way - perhaps a year/year and a half away from the Federation, and humanity. 

This is the key point. 

The Neutral Zone is not a place where humanity has  not gone before. It is the border between Federation and Romulan space. On the edges on each side are outposts - Romulan and Human - that are destroyed by the unknown attackers. 

So... if the Borg were a year/year and a half away from humanity mid-season 2, they could not be encountering humanity at the end of season 1.

Simple as that...

(Though all of the first contact with humanity was later contradicted by ST: First Contact, Voyager, and Enterprise... ho-hum...)