Phonological deviations in formal political speech constitute a productive site for investigating the intersection of language error, dialectal interference, and sociophonetic identity. Despite a growing body of research on language errors in Indonesian political discourse, the phonological profile of President Joko Widodo’s final presidential address, the culminating communicative act of a decade-long presidency, has not been examined. This study addresses that gap through a systematic analysis of phonological deviations in the speech delivered at the Annual Session of the People’s Consultative Assembly (MPR) on 16 August 2024. Employing a descriptive qualitative design with content analysis, the study transcribed the full speech from the official Kompas TV recording and identified deviations using an established phonological error taxonomy. Inter-rater verification was conducted to ensure coding reliability. A total of 29 phonological deviations were identified: 15 phoneme omissions (51.7%), 12 phoneme substitutions (41.4%), and 2 phoneme additions (6.9%). Crucially, the study demonstrates that the dominant omission pattern, including systematic deletion of medial /e/, fricative /h/, and palatal /y/, reflects stable Javanese L1 phonological transfer rather than transient performance error, a finding grounded in the foundational distinction between errors and mistakes in error analysis theory. Drawing on the principle of systematic sociolinguistic variation and psycholinguistic speech production theory, the study argues that several identified forms constitute sociophonetic variation rather than error, and proposes a theoretically grounded error-variation distinction for Indonesian phonological research. Implications for language policy, political communication, and applied linguistics pedagogy are discussed.