Leia is shown giving Edmund a doll, looking like the Witchsmeller Pursuivant. Most likely, given company, it was made by Edmund's mother. At the end of the episode, it's revealed she was a witch. She gave him a poppet to kill the Witchsmeller with. It is a voodoo doll, and it is implied the Queen was in on it...
The end of "Chains" goes some way to explaining why Elizabeth I was "The Virgin Queen".
Myriam Margoyles, a noted lesbian playing the puritanical Lady Whiteadder in the second series episode 'Beer' and in the final scene emerging from under Queenie's skirt... Does that count as a kind of Fridge Actor Allusion?
In the episode "Dish and Dishonesty" in Blackadder the Third, Edmund says that he'll be back before the prince can say "antidisestablishmentarianism". It just seems like a long funny word, which the prince, who is an idiot, is unable to figure out how to pronounce before Edmund returns two days later. But, the word itself basically means "the movement of people against people who are against the establishment". Especially it refers to a 19th century political movement against the separation of the Church of England and the government. The prince is actually Prince Regent and thus effectively the head of the Church of England and the British sovereign, the whole series (sort of) takes place in the early 19th century, and Edmund is going out to recruit an MP to support the prince and oppose those who are seeking to remove him power—thus antidisestablishmentarianism is exactly what they are doing!
In the Blackadder Christmas Carol, it would have made no difference in status if Blackadder had been nicer and so gotten the money and a title from the queen - he was horrible so he didn't get it, but if he had been nice and gotten the rewards, he probably would have ended up giving it all up to the poor.
Each significant member of the Blackadder line is slightly smarter and more competent, building on the mistakes of the past, until he finally wins. Now it makes sense that Edmund I was a complete idiot!
Clearly it's not above Mr. Blackadder to take the Prince's identity when the opportunity arised, but after all, George promised him "everything", and Blackadder himself fulfilled his promise to die on his friend's behalf. Technically, he's only taking what was promised. The rest was Fate being kind to him.
In the final episode of Blackadder Goes Forth, Baldrick comes up with a "cunning plan" involving a splinter on a ladder. At first this seems like comedic Noodle Implements, but pay attention to what he says- he says "that's a rather nasty splinter on that ladder, someone could get hurt." His plan was essentially to do something to the ladder so that when Edmund climbed out of the trenches, the ladder would break and he'd fall, possibly breaking a leg in the process and getting sent to the hospital (and thus avoiding the dreaded "Final Push").
In "Blackadder Back and Forth", Blackadder travels back in time and steals Robin Hood's girlfriend. In the second season Lord Flashheart, a descendant of Robin Hood, stole Blackadder's fiance.
"Blackadder Back and Forth" features the modern descendants of the entire main cast from different periods of history, assembled with a time machine in their midst. This creates infinite possibilities, especially with Lady Elizabeth who looks like she would travel back in time and pull a Prince Ludwig on Queenie in a heartbeat.
The dying Blackadder in the last episode of season one should logically be screaming in agony, after his genitals, ears and hands have been chopped off. He isn't. He does, however, seem to have no strength left and carries physical injuries. Now bear in mind that Gertrude was a witch, who had used her powers to save her son's life before and another layer is added to the story. Of course if she did manage to completely save his life she wouldn't have shown it at that time, so as to protect her own life. We will never know, as she and Blackadder both drink poison and die.
What if Samuel Johnson's ghost took revenge on the Blackadder family by corrupting Ebenezer Blackadder so that he wouldn't get the money from Queen Victoria?
In "Chains", Lord Melchett gets the line, "As private parts to the gods are we! They play with us for their sport. The joke here is not only a play on a famous line from King Lear ("As flies to wanton boys, are we to the gods. They kill us for their sport."), it also plays on a thematically similar line from The Duchess of Malfi ("We are merely the stars' tennis balls, struck and banded which way please them.") Note that Stephen Fry, who plays Melchett, went on to write a retelling of The Count of Monte Cristo called The Stars Tennis Balls.
Near the end of "Goodbyee!", Edmund says, "The guns have stopped because we're about to attack. Not even our generals are mad enough to shell their own men. They think it's far more sporting to let the Germans do it." According to the Real Life section of Trial by Friendly Fire, the orders to walk slowly towards the enemy were intended to keep the troops behind the barrage of shells so they will have cover fire. By ceasing fire for the charge, the generals are just showing once and for all that they're deliberately trying to get everyone killed.
Also, Darling's line in the final episode. "The Great War: 1914 to 1917". To think that this insanity will continue for yet another year is almost too awful to contemplate.