Politics
The plot of Visit to a Small Planet concerns Kreton, an alien visitor, who invades a middle-class home in 1957 America. After he announces his plans to engage the world in a full-scale war for his own entertainment, the characters respond to this threat in ways that reveal their political ideas and ideals. Kreton has used his powers of mind to levitate all of the rifles in the world for fifteen seconds and both General Powers and Roger Spelding assume the Russian Army is behind the stunt. Roger explains to his television audience that the Russians have "launched a new anti-gravity force which suspended all the rifles in the free world some fifty feet off the ground." He continues by stating, "late this afternoon ... Moscow, in an obvious move to avert suspicion, accused the United States of lifting all the rifles in the Communist world one hundred seven feet off the ground." Later, Powers asks Kreton if the United States can officially announce his arrival, for they would like him (and themselves) to "get the best possible break, publicity-wise." These are only some of the ways in which Vidal mocks the United States/Soviet rivalry as well as the then-prevalent American fear of Communism.

Earlier examples of political paranoia occur when Kreton is interviewed by Powers. He tells the alien, "you'll die if it turns out you're a spy or a hostile alien or something like that'' and that he suspects Kreton to be "sent here by an alien race to study us, preparatory to invasion." Kreton, however, is above such trivial concerns as land acquisition, and his cool indifference to Powers exacerbates the General's rage. Later, Powers informs Kreton that he has been "classified as a weapon" and that the Pentagon expects a detailed list of his "powers." Visit to a Small Planet satirizes politics, revealing the insincerity of its highest ranking officials. Vidal presents politics as little more than a forum for ego-satisfaction and personal gain. Ultimately, Vidal's play invites viewers to notice the fear and suspicion that play such a large role in modern politics while also highlighting what he seems to see as a contradiction in the phrase, "military intelligence."

Patriotism
Closely connected to Vidal's political issues is his examination of patriotism. While author Samuel Johnson once defined patriotism as "the last refuge of a scoundrel,'' Visit to a Small Planet shows how different people define "love of one's country."

When he first suspects Kreton of being the representative of a foreign country, General Powers attempts to display his patriotism by telling him, “if your people are thinking of an invasion they should know that we're ready for them. We'll fight them with everything we've got. We'll fight them with the hydrogen bomb, with poison gas, with broken beer bottles if necessary. We'll fight them on the beaches; we'll fight them in the alleys." Powers equates "patriotism" with military might and assumes that his definition of the term—and his fervid devotion to American—will intimidate Kreton.

After Kreton's threat of war becomes more of a possibility, Roger tells Conrad that he should enlist in the Army; Conrad, however, refuses because he "doesn't want to fight anybody." His pacifism directly opposes General Powers's display of "rough and ready" American spirit. This shocks Kreton, who asks, "Do you love your country?" When Conrad says that he does, Kreton's response shows his own understanding of American patriotism: "Then don't you want to slaughter its enemies'" After Conrad shakes his head, Kreton states, “that’s the wrong answer. That is not a proper mid-twentieth century sentiment." Vidal is using Kreton as a way to illustrate Conrad's pacifism and suggest that not all patriots and "good Americans" equate "loving one's country" with a desire to "slaughter its enemies." Kreton begins singing old military songs in order to stir patriotic emotions within Conrad; when these fail, he begins evoking names from popular legend and entertainment: "Davy Crockett stood by his guns! Remember the Alamo! Remember the Maine! Remember Errol Flynn on the Burma Road!" However, none of these have any effect. Conrad's attitude towards war is meant to be seen as a more reasonable form of patriotism than that offered by General Powers. Kreton's inability to understand Conrad's ideas shows the alien's simplistic view of what patriotism entails.

Sex
A subplot of the play involves Conrad and Ellen's love affair. When the play begins, they are planning to check into a hotel under the names "Mr. and Mrs. Ollinger''; they have even filled a suitcase with old telephone books and plan on telling Roger that they are "going to the movies." Their furtive sexual scheming is mocked by Kreton, who tells them that, on his planet, sex does not exist, since they have rid themselves of all forms of passion. Throughout the play, Vidal explores American attitudes toward sex by having Kreton attempt to discover why Americans make such a fuss over it. When he asks Ellen if he can watch (for scientific purposes) her "tangle" with another man and is informed by her that his request is "disgusting,'' the mind-reading alien responds, "but... but it's on your minds so much I simply assumed it was all quite public." Ellen explains that, in America, "we do think an awful lot about sex, but we're not supposed to talk about it and we only do it when nobody's looking." This attitude toward even the mention of sex is questioned by both Vidal and Kreton, who remarks, “these primitive taboos. You revel in public slaughter, you pay to watch two men hit each other repeatedly, yet you make love secretly, guiltily and with remorse.'' This conversation is one in which the audience is invited to question what Vidal sees as a contemporary contradiction: talking about violence is perfectly acceptable and decent, while sex is a forbidden topic and is reduced to a "primitive taboo."