The pair both drowned in a hotel swimming pool after Ronnie (played by Samantha Womack) tied the knot with Jack Branning (Scott Maslen) and they went for a midnight swim.
Viewers rushed to watch the alternate clip, which saw Ronnie survive while her sister suffered a watery death.
But many were outraged when the BBC delayed the unveiling of the video despite teasing the content throughout the evening.
Taking to social media, fans of the BBC soap demanded that the members of staff responsible for the delay be fired for the gaffe.
One viewer raged: “Whoever is in charge of the @BBCOne snapchat needs to be fired!! Where’s the alternative ending at?!?! #eastenders.”
Another added: “Hurry up #eastenders I’m waiting for the EastEnders alternative ending on Snapchat teasing us with snippets omg play it already #Eastenders.”
“Hmmm was this a plot to get us gullible lot to add the BBC #snapchat account to see the alternative #eastenders ending?! It’s not there!,” a third asked.
EastEnders continues on BBC One tomorrow night at 8pm.