Romanes eunt domus
Languages other than Japanese are extremely common in the Puella Magi franchise. As such, sometimes silly grammatical or semantic errors are made. This page is devoted to those errors.
The name of the series itself
Puella magī Madoka magica appears to be intended to translate to "magical girl, magical Madoka." However, puella magī is not the correct Latin way of rendering "magical girl," nor even the obvious error "girl of magic" -- magī is the genitive singular of magus, meaning "mage," so puella magī would translate to "girl of the mage." To render "magical girl" correctly, it may be better translated as puella magica. ("Girl of magic" would be puella magiae.)
Named attacks
Iroha Tamaki: Strada Futuro
Strada is an Italian noun meaning "road," and futuro can be either a noun or adjective meaning "future." If it is a noun, it needs an additional particle (in this case del) to be marked as possessive. Or if it is an adjective, it needs to inflect to match the (feminine) gender of strada. Thus, it may be better translated as Strada del Futuro (if it is to be taken as "road of the future") or Strada Futura (if it is to be taken as "future road").
Rumor Sana: Elektron Schwert
German for "Electron Blade," it is spelled in Japanese with the center dot that represents a word boundary (エレクトロン・シュヴェールト). However, German forms such compound nouns without a space in the middle, so it should be Elektronschwert (エレクトロンシュヴェールト).
Ui Tamaki: Luce Speranza
Like her sister's, Ui's Magia name is two Italian nouns mashed together (luce meaning "light" and speranza meaning "hope"). However, luce can also be the third-person singular present indicative of lucere, an intransitive verb meaning "to shine," so it could be interpreted as meaning "Hope shines!" -- except that Italian only inverts the word order in dependent clauses[Citation needed], which a standalone attack name is not. As such, if it is to be treated as a verb phrase it may be better translated as Speranza Luce, and if it is to be treated as a noun phrase as Luce della Speranza.
Umika Misaki: X File
Pronounced イクス・フィーレ (Ikusu Fīre). Like her teammates, Umika named her special attack with an Italian translation of the name of a TV series (The X-Files). However, the Italian word file in the attack name is specifically used for a "file" in computing; whereas the name of the show refers to a "file" (physical archive) of unexplained phenomena. As such, it may be better translated as X Archivio.
Hinano Miyako: Atomo Arrabiato
In earlier versions of the game, Hinano's Magia used the feminine version of the adjective for a masculine noun; this has since been fixed and her Magia name is 'Atomo Arrabiata'.
Names of witches
Misspelled witch names are extremely common in Kazumi Magica, since all of the named witches have German words as names. These may have been intentional, since they are fairly prominent.
Airi Anri's witch form: Nie Blühen Herzen
Translating to 'never blooming hearts', but 'Blühen' should be 'Blühende'; 'nie blühen herzen' would translate to 'never bloom hearts'.
Yuuri Asuka's witch form: Arzt Kochen
The name of the witch was likely supposed to translate to 'cooking doctor', but the order of words makes it 'doctor cooking'.
Song titles and lyrics
Yuki Kajiura -- Wo ist die Käse?
The title and most prominent lyric of Nagisa's theme is intended to translate to "Where is the cheese?" However, Käse is a masculine noun, so it would take the article der. This can be avoided by treating Käse as plural, so it takes die anyway regardless of its original gender, but then the verb is incorrectly conjugated -- ist is third-person singular ("where is the cheeses?"), and the third-person plural would be sind. As such, it may be better translated as either Wo ist der Käse? (singular cheese) or Wo sind die Käse? (plural cheese).