Dreamscape

Dreamscape is a Science Fiction film directed by Joseph Rubin (The Forgotten, Sleeping with the Enemy), starring Dennis Quaid (Vantage Point). The film was released in the United States in 1984 by 20th Century Fox. Dreamscape was ranked #93 on Rotten Tomatoes list of the top reviewed scifi films. The plot is loosely based on the novel The Dream Master by Roger Zelazny.

Alex Gardner (Quaid) is a man with special talents — psychic talents, to be exact. While participating in ground-breaking studies on the powers of the mind at the age of 19, he suddenly quit and attempted to disappear, from then on only using his abilities for petty personal gain. Years later, his extraordinary "good luck" both at the race track and with the ladies has drawn the attention of unsavory eyes... and now he and his talents are in high demand by everyone from local gangsters to shady government agents.

When Alex is contacted by the college professor that performed the studies on him years ago, Alex agrees to hear him out, both for old times sake and to have a place to momentarily hide from everyone who wants a piece of him. When the professor explains what he's working on -- a project that will allow those with psychic abilities to enter the dreams of others -- Alex is intrigued, and with a little "convincing" agrees to help out. With the professor's assistance, Alex is quickly able to master the ability of entering, observing, and even modifying people's dreams. At first he feels exhilarated, intoxicated by the freedom and power that come along with his new-found ability. However, things are not quite what they seem... inside the Dreamscape, Alex finds that he is facing progressively more dangerous nightmares, and outside he must deal with the schemes of not only a rival psychic, but also of the shadowy machinations of the people who are truly behind the Dreamscape project.

Tropes used in Dreamscape include:

Actor Allusion: Alex meets author Charlie Prince, played by George Wendt, in a bar... where one would often see Wendt in his most famous role, "Norm" from Cheers.
After the End: The President's nightmares take place in the flaming ruins of a nuked city.
A God Am I: Tommy Ray Glatman: "In this world, Alex, you're nothing. And me, I'm God."
Beat Still My Heart: After Tommy Ray rips a security guard's heart out of his chest.
Dangerous Windows: The Snake Man breaks in through a window to grab Buddy.
Dream Spying
Half-Human Hybrid: The Snake Man.
I Know You're Watching Me: It becomes clear to the scientists secretly observing Alex through a two-way mirror that he knows what's going on when he writes "Let's get on with it" on his side of the mirror in pen... especially since he writes the letters backwards so that those on the other side can read it.
Infant Immortality: Played straight with Buddy; in the President's dream, the kids trapped in the ruins aren't just dead, but mutilated to Body Horror levels.
"It's Not Rape If You Enjoyed It": Alex's rationalization for covertly inserting himself into Jane's dreams to make her think she was having a sex fantasy about him, rather than making out with the real life person. The fact that she enjoyed herself doesn't negate the fact that he just basically raped her (Mind Rape?), as she was in no position to give informed consent.
Mind Over Matter: Minor telekinesis is among the range of Psychic Powers Alex displays over the course of the film. It never becomes the Chekhov's Gun, and stays an Informed Ability.
Minor Crime Reveals Major Plot: When a subject is killed in the real world by dying in the Dreamscape, Alex starts to realize he's in over his head... what he doesn't know is that the government is training his rival, Glatman, to assassinate people in their sleep.
Monumental Damage Resistance: During a recurring nightmare the President of the United States is experiencing, a partially destroyed Capitol building is seen in the ruins of Washington, D.C., after it was ravaged by nuclear war.
Never Sleep Again: Tommy Ray Glatman assassinates people by using his psychic abilities to enter their dreams and kill their dream selves.
Or Was It a Dream?: The train conductor is the same man in both trains, both in the dream and in the real world.
Our Presidents Are Different: President Target, at least where dreams are concerned; in the real world he's more President Iron.
Partial Transformation
Pistol-Whipping: Alex pistol whips a federal agent while re-infiltrating the project facility.
Red Eyes, Take Warning: The wolves pursuing Alex and the President.
Reptiles Are Abhorrent: The nightmares of a young boy Alex is trying to help take the shape of a half-man/half-snake creature. One of the villains also later assumes this form while in the dream world.
Your Mind Makes It Real: Not only is Alex capable of causing himself severe mental damage while in the Dreamscape, but both the subjects and the psychics helping them can be killed in real life if they die while dreaming.
Your Worst Nightmare: What Alex tries to help his subjects overcome.