I have some pretty cool ideas for a fast emergency end:
1) The blone FBI chick wakes up in her bed -> everything was just a dream! She gets up, checks for Tyler who's in his room jacking off to some internet porn. That's when she realizes that everything is fine and as usual. She goes into the kitchen and makes some coffee. (Totally cool and unexpected end)
2) Anna suddenly and unexpectedly dies from hemorrhoids. The Vs are shocked and decide to go home now where they're without queen.
3) The Vs find out too late that Tyler carries HPV and a bunch of other STDs. The whole V population is already infected. They have no other choice than to self-destroy the mothership after they tortured Tyler to death for infecting the whole V ship.
The 5th column rejoices and has a huge beach party with beer n' tons of naked chicks.
4) All of a sudden other, even more malevolent, aliens show up who followed the Vs all the way from their home planet. They destroy all V ships with untraceable supersilent space torpedos. After that they also destroy the earth with a super strong nuclear missile before they take off into outer space.
5) Anna suddenly decides that Tyler is not a good sperm donor. She thinks that an italian stallion would be best to create a new generation of super Vs. Unfortunately she does not survive the mating act with the stallion who splits her in two. (Totally sad end with sad music and everything)