This movie had a very high box office in mainland China.
Tips
culture
In Hong Kong and Macau, 内地 specifically means mainland China. In a general geographic sense, it means the inland/interior areas of any country, as opposed to coastal regions.
usage
内地 vs 大陆 (dàlù): Both can mean 'mainland China', but 大陆 is more commonly used in Taiwan, while 内地 is used in Hong Kong/Macau.