Computable legal contracts offer a formal structure and semantics that can help identify incompatibilities among clauses, such as clauses that will never be used or clauses whose simultaneous application is impossible. In this paper we study a methodology for spotting incompatibilities in contracts written in Stipula, a domain-specific language for legal contracts. Drawing on real case laws, we identify recurring incompatible code patterns and propose techniques for integrating their analysis in the Stipula toolchain.