《西游记》有哪些隐晦内容和暗示？

1、孙悟空的金箍棒，重13500斤，照应人昼夜呼吸13500次（评论区有解释）。
2、金箍棒，原是天河定底神珍（or 神珍铁），不是定海神针。是神珍，不是神针。
3、原著中，多次出现1、3、5这三个数字。比如金箍棒是13500斤；孙悟空在地狱中的魂魄排号为1350号；唐僧，孙悟空，猪八戒，沙僧和小白龙共同组成的取经团队，1个师父，3个徒弟，5个人。
4、唐僧确实不只有悟空，八戒，沙僧三个徒弟。早在取经之前，唐僧在洪福寺里修行的时候，就有不少凡人徒弟了。唐僧还对凡人徒弟们说，自己发下誓言，等寺庙山门里松枝头向东的时候，自己就会取经归来。
5、猪八戒的九齿钉耙和沙僧的降妖杖都是5048斤，唐僧师徒从西天取回的一藏经卷共计5048卷，取经之路历经一十四年，来回共计花费了5048天的时间。
6、“佛子还来归本愿，金蝉长老裹旃檀”是西游记第八回当中的一句诗词，这句诗词暗示了将来唐僧是要成佛的。唐僧是金蝉子转世，金蝉脱壳才得自在，脱下蝉壳裹上旃檀，旃檀是雕刻佛像的木头，裹进去就是成佛了。
7、悟空，悟能，悟净。“悟”，拆开来看，就是“吾”和“心”，即代表自己的心。悟空，即是吾心空，悟能，即为吾心能，悟净，即为吾心净。三人名字排列组合，便是吾心净就能空；或者是吾心空就能净。
8、地狱十八层，是眼、耳、鼻、舌、身、意六根，作用于色、声、香、味、触、法六尘，而生起的喜、怒、哀、思、忧、郁六识。悟空在第十四回中打死的六个盗贼，一个唤做眼看喜，一个唤做耳听怒，一个唤做鼻嗅爱，一个唤作舌尝思，一个唤作意见欲，一个唤作身本忧。孙悟空看似是杀了强盗，其实是暗示斩断了六根，六根清净，自然就会一心拜佛求经。
9、孙悟空被如来压在五行山之下的时候，正是历史上王莽篡汉之际。到了唐朝太宗皇帝的时候，五行山就改名叫做两界山了，唐僧取经经过两界山救出了悟空。

Sun Wukong's Golden Cudgel weighs 13,500 kg, corresponding to the fact that humans breathe 13,500 times in a day and night (as explained in the comment section).
The Golden Cudgel was originally a divine treasure (or divine iron) from the bottom of the Heavenly River, not the Sea-Settling Divine Needle. It's a divine treasure, not a divine needle.
The original work repeatedly features the numbers 1, 3, and 5. For example, the Golden Cudgel weighs 13,500 jin; Sun Wukong's soul number in the underworld is 1,350; and the team of Tang Sanzang, Sun Wukong, Zhu Bajie, Sha Wujing, and the White Dragon Horse forms a group of five—one master, three disciples, and five individuals.
Tang Sanzang indeed had more than just three disciples—Wukong, Bajie, and Sha Wujing. Even before the journey to the West, when he was practicing at Hongfu Temple, he had many mortal disciples. Tang Sanzang also told these mortal disciples that he had vowed to return from the journey to retrieve the scriptures when the pine branch on the temple's mountain gate pointed east.
Zhu Bajie's Nine-Toothed Rake and Sha Wujing's Demon-Subduing Staff both weigh 5,048 jin, and the scriptures brought back from the Western Heaven by Tang Sanzang and his disciples amount to 5,048 volumes. The journey to the West took 14 years, and the round trip totaled 5,048 days.
The verse "The son of Buddha returns to his original vow, and the elder Jinchan wraps himself in sandalwood" appears in the eighth chapter of Journey to the West. This verse implies that Tang Sanzang is destined to become a Buddha in the future. Tang Sanzang is the reincarnation of the Golden Cicada, who attains freedom by shedding his cicada shell. Wrapping himself in sandalwood, a wood used for carving Buddha statues, signifies his becoming a Buddha.
Wukong, Wuneng, Wujing—"Wu" (悟) means "awaken," and when separated, it forms "my" (吾) and "heart" (心), representing one's own heart. Wukong means "my heart is empty," Wuneng means "my heart is capable," and Wujing means "my heart is pure." The arrangement of their names suggests that a pure heart can lead to emptiness, or an empty heart can lead to purity.
The eighteen levels of hell correspond to the six roots—eyes, ears, nose, tongue, body, and mind—acting upon the six dusts—form, sound, scent, taste, touch, and law—to generate the six consciousnesses of joy, anger, sorrow, thought, worry, and depression. In the fourteenth chapter, Sun Wukong kills six bandits: one named Eye Sees Joy, one named Ear Hears Anger, one named Nose Smells Love, one named Tongue Tastes Thought, one named Opinion Desires, and one named Body Fears Sorrow. Although Sun Wukong appears to kill bandits, it actually implies severing the six roots, achieving purity, and naturally devoting oneself to Buddha and the scriptures.
When Sun Wukong was trapped under the Five Elements Mountain by the Buddha, it coincided with the historical event of Wang Mang usurping the Han dynasty. By the time of Emperor Taizong of the Tang dynasty, the Five Elements Mountain was renamed Two Realms Mountain, and Tang Sanzang saved Wukong while passing through Two Realms Mountain on his journey to retrieve the scriptures.