This is one of those plays which tends to be regarded by audiences and directors alike as being nothing more than a farcical romp as two pairs of twins are repeatedly confused to create chaos on stage. There are, though, deeper implications to the action and the introduction here moves some way towards elucidating some of the contexts and thematic issues which are at stake in the play.
The drama is darkly framed by the possible execution of Egeon, and the problems of identity put all kinds of relationships at risk: marriage, the family, mercantile relations, masters and servants - all the orthodox ways in which early modern society was bound.
So this is a very good edition if you're studying the play or simply want a more complicated way of understanding it - modern ideas of the doppelganger, or even popular comedies like Sliding Doors have more in common with this play that we might at first think.
Like the other Oxford single play texts, this draws on the textual scholarship of the Complete Oxford but with extended commentary and notes which make it particularly useful for students.
Identical twins have only one purpose in movies and plays: to cause mass confusion when people mix them up.
So the mayhem is doubled in "The Comedy of Errors," which has not one but TWO sets of identical twins who are totally unaware of each other's existence. Shakespeare's adaptation of a Plautus play is basically non-stop wackiness and slapstick, without much plot besides the two Antipholuses and the two Dromios constantly being mistaken (and sometimes mistaking each other) for their twin brothers.
The Syracusan merchant Egeon is condemned to death in Ephesus for entering the city, for... some reason that's never very well explained. He can only be saved if he pays one thousand marks within one day. So he tells the Ephesian Duke his tale of woe -- his wide Aemilia gave birth to identical twin boys, on the same day a poor woman also produced identical twin boys to be their slaves. But then his wife, one baby and one slave baby were lost in a shipwreck, leaving Egeon with the other twins. Now Antipholus has gone out in search of his lost twin, accompanied by his slave Dromio.
Got that? It's pretty much the setup for the whole plot. Here's the problem: the missing twins are actually in Ephesus, and are also named Antipholus and Dromio. Even better, neither of them has any weight, scars, haircuts or fashion eccentricities that keep them from being mistaken for each other. What wackiness!
So when Dromio (Ephesus) mistakes Antipholus (Syracuse) for his master, he ends up getting his butt kicked -- and even worse, Antipholus' (Ephesus) wife Adriana mistakes Antipholus (Syracuse) for her husband and thinks he's cheating on her. But her unknown brother-in-law-mistaken-for-her-husband instead falls in love with her sister. Oh, and Dromio (Ephesus) also has a comically unattractive wife, whom Dromio (Syracuse) is desperate to get away from. Wackiness!
While she dines with his identical twin, Antipholus (Ephesus) is irritated at being locked out his house, dines with a courtesan and orders a gold chain... all of which causes even more madcap antics: arrests, accusations of theft, the Dromios getting their butts kicked again, and Adriana thinking her husband is cheating, crazy and/or possessed.
As evidenced by the summary, "The Comedy of Errors" doesn't have much actual plot. It has exactly three things going on: A) Other people mistake one Antipholus/Dromio set for the other; B) Either Antipholus or Dromio (either one) mistakes the other for his brother (or vice versa). C) Either Antipholus/Dromio pair gets in trouble for something the other ones did.
So our dear Willie Shakespeare frolicks in farce, skips through slapstick and cavorts through comedy. This isn't exactly his wittiest or subtlest play he wrote (Dromio compares his sister-in-law's butt to Ireland because of the... um, peat bogs), but it shows his considerable skill at juggling a complicated plot, lots of accusations and misunderstandings, which all ultimately culminates in a massive goofy confrontation between all the characters. In fact, I'm shocked Hollywood has not adapted this yet.
A lot of the comedy comes from Shakespeare's many silly word puns, topical jokes (Nell's forehead is France, because it is "armed and reverted, making war against her heir"), and the Antipholuses constantly beating up the Dromios. There is some occasional pretty verbal wooing ("Spread o'er the silver waves thy golden hairs/And as a bed I'll take them and there lie"), but it's mostly reliant on puns and gags.
The one problem? This is one of those stories that requires the entire cast to be idiots. Admittedly there wouldn't be a plot if they WEREN'T idiots, but none of them ever make the connection of "missing identical twins" with "people claiming I did and said things I didn't do."
It's genuinely amazing that Hollywood hasn't yet adapted "The Comedy of Errors," because Shakespeare's fluffiest comedy is perfectly suited -- mistaken identities, mayhem, gags and slapstick.