Characters wear revealing clothing at certain points, including tank tops, short skirts and low-rise jeans.

Some hugging between friends.

A character is mortally wounded, seen lying on the ground and breathing heavily. This same character is later killed; his shadow is seen on a wall being lifted up by a clawed hand, after which his upper body is torn off while he screams. The observing protagonists are visibly upset by this.

Aliens resembling large banana slugs are depicted slithering into the ear canals of human beings to control their brains. Actual slugs are seen entering and falling from peoples' ears; the series intro theme credits features a brief CGI rendering of this fictional process.

A boy touches a live butterfly's wings (which is commonly known to injure them to the point where they are unable to fly).

Characters "morph" into different animals, and in one case, into an alien. Grotesque bone-crunching is heard.

A man attempts to step on a live salamander and squash it to death.

A few slang terms and mild name-calling, but no swearing.

A man crawls beneath movie theatre seats in the dark, eating food which people have dropped. He crawls beneath a little girl's seat to grab up some discarded popcorn, and accidentally "morphs" into an alien, causing her to scream.

A few scenes of mild peril, including a character being chased by an alien, a boy being turned into a falcon (unable to change back), characters being trapped in places, animals being chased, and a girl whose father appears to be possessed by an alien. These scenes may frighten some viewers.

A boy hides in a garbage truck. The truck has a compacting mechanism in the back to crush down the garbage flat. It appears that the boy has been crushed to death, but it is later revealed that he has escaped unharmed.

There are large animals often shown in this series, including roaring lions with sharp teeth. At one point, a lion appears from nowhere and knocks a man into a swimming pool. This may frighten some viewers.

The entire series often features an unsettling tone, incorporating spooky background music and thematic shots into the show to set the scene. This may frighten younger viewers.