The genetic information is transcribed from DNA into a messenger RNA template and the latter then acts as a messenger to synthesize proteins in a process called translation. Before this last process, RNA splicing facilitates the removal of introns from the primary RNA transcript, leaving exons, which are joined to produce mature mRNA. In human, alternative patterns of pre-mRNA splicing produce different mature mRNAs containing various combinations of exons from a single pre-mRNA, in a post-transcriptional modification called alternative splicing. This means that, the expression of a single gene can result in multiple proteins. As these proteins differ from each other, they exert different biological functions and may affect various disease conditions. To understand how this mechanism contributes to disease, we profile transcriptomic data from mouse embryos in which core components of the spliceosome were mutated. Using RNAseq and a suite of bioinformatic tools we compared alternative splicing patterns between wild-type and mutant embryos. We also characterized the splicing signals (sequence elements that are located at the 5′- and 3′-splice sites, the polypyrimidine tracts, and the branchpoint sequences) that are associated with alternative events found in wild-type and mutant embryos. We uncovered significant changes in alternative splicing patterns and splicing signals in mutant embryos. Our robust bioinformatic pipeline will be used to facilitate a better understanding of the contribution of alternative splicing to embryonic development.