Board Thread:Plants vs. Zombies 2: It's About Time/@comment-22512055-20140321135046/@comment-24275721-20140325142315

That is actually a spaceship fitted with a time machine device. At least that's my theory:

1. They need to travel to places in the past (the front lawn) so they need a time machine.

2. The past always won't look the same and the zombies won't walk everywhere so they need a travelling locomotive.

So that red thing is both of the above.