“After Earth” (PG-13): Parents may groan at some of the corny dialogue and melodrama that director and co-screenwriter M. Night Shyamalan injects at odd, awkward moments in “After Earth.” Yet kids 12 and older may still find the flawed sci-fi adventure an involving roller-coaster ride.

Will and Jaden Smith, father and son in real life, play Cypher and Kitai Raige, respectively. In a confusing prologue, Kitai explains that it is 1,000 years in the future.

Earth was abandoned in the late 21st century, too polluted for humans. Survivors were evacuated to a planet called Nova Prime, where Cypher is a heroic lead Ranger. He protects people from the savage Ursa monsters that evolved on Nova Prime to attack humans.

His utter fearlessness makes him invisible to the Ursas. Gangly Kitai aces his studies, but still lacks the maturity to become a Ranger. Kitai can’t confide his roiling feelings to his stern and distant father.

So Cypher, at his wife’s (Sophie Okonedo) urging, takes Kitai along on a mission for some father-son bonding.

The spaceship hits an asteroid shower and crashes onto contaminated Earth. Kitai and his dad are the lone survivors. Cypher’s leg injuries mean he must send his untested son alone on a perilous trek to retrieve an instrument that will project a beam into space for their rescue. It is in the tail of the ship, 100 kilometers away. Kitai is threatened by mutated Earth animals and an escaped Ursa from the ship’s hold. He communicates with his weakening dad via a holographic gizmo on his sleeve, and survives the bad air with a liquid that coats his lungs. He is on a hero’s journey, and the theme about facing fear does resonate.

The PG-13 reflects violent and scary moments that become quite intense and even bloody. Young Kitai fights the shrieking Ursa monster, which looks like a huge insect-reptile hybrid.

The hatchlings of a giant bird are killed – not too graphically – by mutant mountain lions. Kitai sees dead crew members impaled on tree branches and dead animal carcasses.

Back at the ship, Cypher performs surgery on his own broken leg.

Kitai recalls in many flashbacks the death of his big sister (Zoe Kravitz), who was attacked by a monster when he was too little to protect her. There is no profanity and one instance of mild sexual innuendo. Phobics note: Kitai meets a large spider, a herd of angry apes and a big snake. His face and body swell after a leech bites him.

“The Hangover Part III” (R): Downsized from the raunchy guys-on-the-loose farces that preceded it (“The Hangover,” R, 2009; “The Hangover Part II,” R, 2011), Part III is just a caper comedy, albeit still adults-only and with outrageous bits tacked on here and there.

We get lots more about Alan’s (Zach Galifianakis) mental illness, which is only dubiously droll.

Off his meds and still living with his rich parents at age 42, Alan’s behavior goes beyond inappropriate.

We first see him driving down the highway hauling a trailer with a giraffe in it. The poor animal gets beheaded at an overpass (all computer-animated, no doubt). This elicits laughter that’s mainly shock.

After his dad (Jeffrey Tambor) dies of a heart attack right behind him while the oblivious Alan rocks out in his headphones, his family and pals stage an intervention.

Phil, Stu and Doug start driving him to a treatment center, but they’re run off the road and abducted by men in pig masks.

A gangster (John Goodman) takes Doug hostage and demands that Phil, Stu and Alan find the nutty criminal from the earlier films, Mr. Chow (Ken Jeong), who has stolen millions in gold from him.

We know from the prologue that Chow has escaped from a Bangkok prison.

The trio drives to Las Vegas (where Alan falls lustily for a pawn shop clerk played by Melissa McCarthy) to find Chow. As usual, he nearly gets them all killed.

Lethal, if relatively bloodless gun violence occurs a couple of times.

The script contains intensely crude sexual language, very strong profanity and strong sexual innuendo involving a lollipop. Characters drink, smoke and use knock-out drugs. There are topless women and a couple of frontal male nude scenes.