 Mimzy is the last one remaining, but is now beginning to disintegrate.The reason for the deaths of all the other rabbits is the "chosen ones" before Emma had no "engineers" (like Noah) to help build the bridge across time.Emma and Noah must build the bridge by using the other toys to activate a time portal, so that they can return Mimzy to the future with uncorrupted 21st-century human DNA that the people of the future can use to correct the damage to their DNA caused by ecological problems.