Behold, the reason so many people diss the original Doctor Who and its horrendous special effects. The disastrous dinosaur effects in the Who story "Invasion of the Dinosaurs" are legendary, and here's a clip from the new DVD featurette exploring just how they went so wrong. And they did go so very, very wrong.

The investigation of this dinosaur disaster is just one of the many great pleasures on two new DVDs, "Invasion of the Dinosaurs" and "The Android Invasion."

The two latest Doctor Who stories on DVD have a number of things in comon:

• They're both somewhat underrated examples of good solid storytelling from classic Doctor Who
• They both feature the Doctor and Sarah arriving in a mysteriously deserted present-day England
• They both have the word "Invasion" in their title
• They both feature Elisabeth Sladen at her absolute best as Sarah Jane Smith, getting into trouble and kicking ass
• They have villains whose plots are so ludicrously overcomplicated, you can't possibly make sense of them.

And most of all, the two stories represent the tail end of UNIT, the paramilitary organization the Doctor joined up with in the 1970s — "Invasion of the Dinosaurs" is Jon Pertwee's last real UNIT adventure, although they reappear during parts of his final story. And "Android Invasion" is the first UNIT story not to feature Brigadier Lethbridge-Stewart, and has a distinct feeling of the writing being on the wall for the Doctor's soldier friends.

But for all that, they're pretty good showcases for UNIT — there's an invasion in both stories, of sorts, and UNIT is dealing with it. Both stories tease the possibility that UNIT might not be the Doctor's most reliable allies after all — in "Dinosaurs," non-UNIT soldiers arrest the Doctor, and later actual UNIT soldiers are ordered to arrest him as well. In "Android," the UNIT soldiers turn out to be android replicas, who are also out to get the Doctor. In the end of both stories, though, UNIT comes through and proves itself reliable and steadfast after all.

Oh, and those convoluted plots are really quite convoluted. In "Dinosaurs," some eco-friendly mad scientists cause dinosaurs to appear in London so they can clear the city of people — for what reason, we never learn — and trick a bunch of extremely silly thought leaders into going into a fake spaceship for months. Their actual plan — spoiler alert — is to turn back time so that they can live in the idyllic unspoiled past and prevent civilization from developing in the same way. (Much like Terra Nova, actually.) In "Android," some aliens build a perfect replica of an English village on another planet and fill it with android replicas of real people, to prepare them to invade the real Earth. Oh, and they capture an astronaut and convince him that he's missing an eye.

The most notable thing about "Invasion of the Dinosaurs," other than the horrible dinosaurs themselves, is the fact that the first episode was destroyed, and is now only available in grainy black and white. The DVD actually has the option to view episode one in restored color, and to my non-expert eyes, it actually looks not bad. It's really nice to be able to have the whole story match.

The DVD features on both discs are pretty great, actually. On "Dinosaurs," there's a better-than-average making-of featurette, which talks about the politics of the story. (Snippet at left.) And there are actual honest-to-goodness deleted scenes, which few stories from this era actually have, and they do add a bit to the appreciation of the story and the choices that were made in editing it.

There's also a look at director Paddy Russell, one of the few female directors on Doctor Who, and the lengths she went to to film in a deserted London, especially in the first episode. Oh, and there's a lovely featurette about the late Elisabeth Sladen and her memories of her first year of Doctor Who, featuring an interview with her where she's in high spirits. Oh, and there's another one of those "Now and Then" featurettes where they revisit the locations where the story was filmed.

Most of all, though, you get a new appreciation for the Whomobile, the fancy space-age car the Doctor drives in this story and in his swansong. It's Jon Pertwee's baby, which he paid for out of his own pocket, and it appears in the middle of the story for no logical reason other than Pertwee's pride in his new ride.

Meanwhile, "Android Invasion" includes a nice making-of featurette as well, although it's not quite as insightful as the one for "Dinosaurs." And there's a half-hour featurette about what producer Philip Hinchcliffe did after he left the show — which is nice, because you get to see that he went on to have a good career after Who, but also a bit too long, really. And that's about it.

Both stories are worth picking up on DVD, for a nice look at how UNIT stayed interesting even in its declining years. And for Elisabeth Sladen putting her all into being a proactive investigator, running off on her own to look into things and occasionally rescuing the Doctor. Plus, you can always make fun of those ridiculous dinosaurs.