A system for a vehicle includes one or more processors, one or more memory modules, and machine readable instructions stored in the one or more memory modules. The machine readable instructions, when executed by the one or more processors, cause the system to: receive one or more images from one or more imaging sensors in the vehicle; identify a first object in a rear seat of the vehicle based on the one or more images; identify a second object attached to the first object based on the one or more images; determine whether the second object is in a set of objects; and output an alert in response to determining that the second object is in the set of objects.