"It Came" is a love letter to the low-budget science fiction films of the 1950s. The book captures the essence of that era with its charmingly retro setting, quirky characters, and humorous take on the genre's tropes. This theme resonates with readers who have a fondness for vintage sci-fi and enjoy the playful nods to the past.

The character of Doris Night, a capable and intelligent assistant, challenges the traditional gender roles of the 1950s. Her presence and contributions to the mission highlight the importance of gender equality, even in a story set in a time when such notions were not widely accepted. This theme adds depth to the narrative and encourages readers to reflect on societal progress.

The book showcases the quintessentially British traits of resilience and humor in the face of adversity. Dr. Boy Brett and Doris Night's stiff upper lip and witty banter provide a lighthearted contrast to the dire situation they face. This theme underscores the enduring spirit of the British people and adds a layer of charm to the story.