Kugeza ubu, Joaquin Phoenix numwe mubakinnyi beza kwisi, ariko usibye ubushobozi bwabwo bwumwuga, bizwi cyane kumiterere igoye nubwoko bwo gukora. Mu kiganiro kinini hamwe n'ikinyamakuru GQ, Phoenix yavuze ko mu gihe cyo gufata amashusho ya "Joker" yagize amahirwe yo kugarura undi mukinnyi ukomeye uhagarariwe na Robert de Niro. Itera amakimbirane ni ugushaka kwa Phoenix kwitabira gusoma mbere inyandiko. Ntabwo byari bimeze. De Niro, bahindukiriye umuyobozi Todod Phillips hamwe namagambo nkaya:
Mubwire [Phoenix] ko ari umukinnyi kandi agomba kuba mu mwanya ... Ndashaka kumva film burundu, bityo rero twese tuzateranira mucyumba kimwe kandi dusome inyandiko gusa.
Phoenix yashubije ibi:
Ndumiwe hamwe abiri, ntabwo nzitabira tweet.
Nkuko mubibona, umushyigikiye inzira ya kera ya de Niro kure ntabwo yahise akorana na Phoenix yambere, ariko kubwibyo, abakinnyi baracyaza kumvikana. Phoenix yavuze ko yemeye gufata tweet mu biro bya de Niro. Nibyo, mugihe cyibirori, Phoenix iracyabyumva mu isahani ye, ntavuga, ahubwo yo kwivuza. Nyuma yibyo, de Niro yatumiye Phoenix mubiganiro byihariye, ariko yanze. Muri icyo gihe, Phoenix yavuze ko yari umufana munini wa mugenzi we mukuru kuva yakinaga muri "Massen Bull" Martin Scorsese.
Uruhare rw'umutwe muri "Joker" rwazanye imbaga ya Phoenix mu bihembo ku giti cye, harimo na Oscar mu gihe cy'amabati "uruhare rwiza rw'umugabo." Hamwe na de Niro, yahawe igihembo gikomeye kabiri - ku ruhare runini muri "Beshen Bull" (1981), ndetse no ku ruhare rwa gahunda ya kabiri muri "Padiri wa Cross 2" (1975).