Continuity mistake: When the three old people throw the car at Ben and Gwen, Ben doesn't have the Omnitrix on for a few seconds. (00:14:10)
Continuity mistake: When the Marty-alien removes the dumpster as Ben watches him, there is a set of stairs leading down. But later, when Ben (as Wildmutt) and Gwen jump down the shaft, the stairs are gone and there is an iron ladder.