This question has been addressed in 1 Texas court opinion:
COA12 — January 30, 2026
In this case, a witness provided surprise testimony during a hearing involving prejudicial information that had not been disclosed during discovery. Although the defendant successfully moved the trial court to disregard the testimony, he did not specifically move for a mistrial. On appeal, the Twelfth Court of Appeals analyzed Texas Rule of Appellate Procedure 33.1(a) and the 'preservation ladder,' which generally requires a party to object, request an instruction to disregard, and move for a mistrial to preserve error. The court held that because the appellant received the exact relief he requested (disregarding the testimony) and failed to seek a mistrial or obtain an adverse ruling, the complaint was waived.
Litigation Takeaway
“Winning a motion to strike or disregard surprise testimony is a 'trap' if the evidence is truly 'incurable.' In Texas courts, if a witness drops a 'bombshell' that poisons the well, you must move for a mistrial and secure an adverse ruling to preserve the issue for appeal. Merely asking the judge to disregard the statement is considered a 'win' at trial that results in a procedural default on appeal, leaving you with no recourse if the judge is ultimately influenced by the excluded evidence.”