Every so often, when Alucard is turned to stone, there is a chance that he will become a giant stone gargoyle. This will make him invincible, but of course unable to do anything.

If Alucard remains seated for a long period of time, he will fall asleep with visible "Z"s. If you have the Fairy familiar, she will also take a rest on Alucards shoulder, only to stumble when he gets up again afterwards. She will also do this if Alucard remains stationary for a prolonged period of time.

Dracula's castle in the boxart of the USA release is Mont Saint Michel, in France.

When using the Rune Sword, the word "Verboten" will appear in its arc. This means "Forbidden" in German.

The Saturn version includes a number of extra areas and features unavailable in the PlayStation version. Most infamously being that of the Underground Garden, as the entrance is still visible in the PlayStation version, though inaccessible. The player can glitch the game into allowing access to this area, but it is unfinished and only a glitched out save point is available.

With the Lyric Card equipped, the player can activate a secret lullaby from the Fairy if Alucard sits in a chair for a period of time. This was only available in the Japanese version of the game, as the familiar that sings it was removed from the international release. But, Konami actually went out of their way to translate this song into English for the PSP version, too.
(Attachment will play both Japanese and English.)

There are a large number of unused dialogue pieces in the Symphony of the Night's data, including what may be an unused ending. Many of these sound files are alternate versions of voices that are already used in the game, but extended or slightly different.

A series of clips can be found in the game's sound files, which seem to be an unfinished ending. It seems to suggest that Maria intervenes in the fight between Alucard and Richter, where she becomes possessed or transformed by Shaft. It includes both winning and losing quotes, and ends with Alucard reflecting on the apparent death of both Richter and Maria. While the PlayStation Portable and Saturn versions allows a fight with Maria, it is not under these circumstances. There are no other suggestions towards this ending, but it is assumed to be an alternate ending during the fight with Richter when not using the glasses.

At the start of the game, Death will take Alucard's equipment. Continuing to the Alchemy Laboratory, and then immediately returning to the room Alucard met Death, the player will be faced with Slogra and Gaibon (the first boss fight). As soon as the player attacks either of them, Gaibon will grab Slogra and fly off, only to be met again in their usual place.

There are two familiars that didn't make the cut during the transition to the Western market. These are the Half-Fairy and the Nose Demon. They are almost exact copies of the normal Fairy and Demon, but with different graphics. They are still programmed into the Western version, but their familiar cards are no longer available, and thus have to be activated using GameShark codes.

The optional boss battle at the top of the Inverted Castle, Galamoth, is a villain from the Kid Dracula series. Although his design is far more gothic and gritty to coincide with Symphony of the Night's style, he retains basic design similarities and even similar lightning based attacks.

In the Inverted Castle, the player must unite 5 relics of Dracula in order to unlock the path to Dracula (Those being a Ring, Heart, Rib, Tooth and Eye of Vlad), a concept first utilized in Castlevania 2. All five are guarded by bosses based on the original Castlevania bosses.

In addition, every boss in the Inverted Castle save one are previous bosses and even playable characters in the series. Aside from the aforementioned five, the player meets Galamoth (Kid Dracula), Shaft (Rondo of Blood), the Doppleganger (Castlevania 3), three falsified heroes from Castlevania 3, with whom Alucard himself was a companion, and of course Dracula. The one exception is Beelzebub, whose first appearance was Symphony of the Night.

In the Spoiler:Reverse Colosseum part of the Upside-Down Castle, there is a boss fight with three ghosts that are named Fake Trevor, Fake Grant and Fake Sypha. These are the doppelgangers of the characters from Castlevania III: Dracula's Curse, with whom Alucard teamed up with to defeat Dracula.

The Clock Tower area is the same as the clock tower from Rondo of Blood, the game's predecessor.

One obtainable item that debuted in this game and recurred in subsequent games is the Stone Mask, which is described in-game as being used in Aztec rituals.

This is a reference to the manga JoJo's Bizarre Adventure, in which a Stone Mask, created by the ancient Aztec people and notable for being used to turn recurring series villain Dio Brando into a vampire, was an important relic in Part 1, "Phantom Blood".

There is a confessional booth in the Royal Chapel area, complete with chairs that the player can sit on. If the player sits on the left hand side of the booth, Alucard sits and leans over to the counter, confessing sins. Sitting on the right will cause Alucard to sit normally as if to hear confessions while a female ghost appears, confessing her own sins or attacking Alucard depending on her color.

If a blue robed ghost priest appears, he sits on the right hand side and hears Alucard's confession, before crossing himself and sometimes leaving behind the Grape Juice item. In the Japanese version of the game (as well as all regional releases of the PSP port) the blue ghost speaks a line wherein he allows Alucard rest in said booth and offers a prayer to God.

While the blue ghost says nothing at all in the US and EU Playstation releases, an unused audio file can be found in the data of a perfect English translation of the blue ghost priest's line from the Japanese version.

"Come, son. Rest here. In the name of the Father, the Son, and the Holy Spirit. Amen."

In the Japanese version of the game, dying as Alucard against certain bosses such as Succubus, Death or Richter triggers a special quote from said bosses instead of the usual Game Over music, with Richter notably having two. Another quote can be triggered if the player dies after meeting Maria in the Royal Chapel but before meeting Richter at the Colosseum

While the US and EU versions do not implement these, there are unused translated versions of Richter, Maria and the Succubus' lines, spoken by their English voice actors.

Maria: "I thought you might be the one. But, I was wrong."

Succubus: "Now, you'll be my own personal slave. Ahahahahahahaha!"

Richter: "Hah, I knew it! Only the Count is a true match for me!" / "More, fight more! My blood is not yet quenched!"