Yep, that's about it. At least that's what I remember. There was a plush toy bunny sent to the past to save the future from the present.
The toy was sent by a John Hurt/Peter O'Toole-looking mad scientist and ends up on a Washington State beach and discovered by two moppets, (the Harry Potterish Noah Wilder, Chris O'Neil) and his cute-as-a-button little sister, Emma (Rhiannon Leigh Wryn, "The Hulk").
The toy comes in a special box with some rocks, a green globule and a glowing rectangle that turns into stone when their mother, Joely Richardson (TV series "Nip & Tuck") touches it.
The special prism divides the earth into compartments that no one on screen (or in the audience) seems to understand the meaning of.
These trinkets also make Noah, a dim bulb at school, turn into a nationwide science fair champion (since he can communicate with spiders and make then spin webs of his choosing). He also has become quite an artist, creating drawings of 12th century Tibetan tapestries and other obscure works of art.
Meanwhile, Emma has become creepily attached to the rabbit, which is an exact duplicate of one Lewis Carrol gave to his young model for "Alice in Wonderland." Evidently, she "learns" from it and soon begins to advocate for its particular mission. She is also designated as a "very special child" by the flaky fiancée, (Kathryn Hahn, TV series "Crossing Jordan"), of Noah's new age science teacher, Larry White (Rain Wilson, TV series "Six Feet Under," "The Office").
Later, while fooling around with the globule, Noah causes an electrical surge that blacks out Seattle, raising the ire of Homeland honcho, Nathaniel Broadman (Michael Clark Duncan, "The Green Mile," "Daredevil").
After arresting the family, which includes befuddled dad, David Wilder (Oscar winner Timothy Hutton, "Ordinary People," bad hair and all), the kids promptly escape and attempt to send the rabbit back to the future with some current genes attached to it.
Overall, this is not a bad film, just a little convoluted, and one which takes almost its entire running time to figure out. The unfortunate thing for "Mimzy" is that it opens with "TMNT" and "The Shooter," which means certain defeat at the box office.