Andrew Gurr (The Shakespeare Company, 1594-1642) identifies one of the primary features of Fletcherian tragicomedy as its conscious efforts to surprise the audience. In the repertory of the King's Men, he cites examples from 1609 such as Philaster, that pull the rug out from under the audience's feet at the end of the play with a surprise revelation, such as a boy character turning out to be a girl (Philaster) or a statue of a dead woman coming to life (Winter's Tale). I'll add Epicoene to his examples, with its woman that turns out to be a boy.
In this light, the additions to Mucedorus, first included in the third quarto of 1610, are rather interesting. In the original version of the play (c.1590), Mucedorus is only identified as a shepherd for the entire play, until the final scene when he suddenly removes his disguise and reveals that he is, in fact, a wandering prince. Gasp! This romantic trope is obviously associated with later tragicomedy, although has its roots in earlier romantic pastoral. However, the 1610 additions are specifically designed to remove the element of surprise. An opening scene shows Mucedorus as prince, donning his disguise and explaining to his friend Anselmo that he is leaving specifically in order to see the princess of whose beauty he has heard report - this is the princess who, on his first appearance in the original version, he rescues from a bear, having apparently stumbled across her by accident. Other additions create roles for Anselmo and Mucedorus' father, reminding the audience of the prince's true identity.
This is interesting because the additions, written in the early years of James' reign (another change is the epilogue, now addressed to James rather than Elizabeth), go directly against what seems to be the emerging structure of the tragicomedy. It may be unsophisticated, but Mucedorus with its disguised traveller, its surprise revelations, its distant climes, wild locations, murders and bears (!) is a good fit for the repertory of c.1610, the drama of the day finally having caught up with the structure of the old play. Yet, at the same time, the play has been adjusted in order to soften those elements which Gurr suggests define the new drama.
I'm going to explore this further, as I think Mucedorus may well have something extremely interesting to say about the development of the tragicomic form within the King's Men at this point. Judging by allusions and reprints, it was one of the most popular plays of its time, and generically it seems to me that it may represent an important turning point in the company's consciousness of how its work was presented.