In other varieties of English, flour and flower are homophones, i.e. they are pronounced alike. In British English, for example, flour and flower are both pronounced /flaʊə/.
In Singapore, however, they are not homophones — ignoring actual vowel quality (i.e. /a, ʌ, ɑ/), flower is /flawə/ while flour is /flaː/. The pronunciation of flour is probably a result of smoothing, in which less salient vowels are dropped.