cardboard

エリザベス女王を描いた“The Queen (2006)”やメリル・ストリープがサッチャー首相を演じた“The Iron Lady (2011)”のようにはいかず酷評されている、“Diana (2013)”の批評からです。

cardboardとは段ボールや厚紙のことですが、形容詞で“seeming silly and not real”(LDOCE)や“lacking depth; artificial”(ODE)と定義されています。芸術作品や、人や物の性格・性質を形容する際に用いられる語のようです。(Sy)

Diana – review

Poor Princess Diana. I hesitate to use the term "car crash cinema". But the awful truth is that, 16 years after that terrible day in 1997, she has died another awful death. This is due to an excruciatingly well-intentioned, reverential and sentimental biopic about her troubled final years, laced with bizarre cardboard dialogue – a tabloid fantasy of how famous and important people speak in private.

http://www.theguardian.com/film/2013/sep/05/diana-review?INTCMP=SRCH