Details of two more exam blunders have been disclosed amid mounting concerns about mistakes in this summer's A-level and GCSE papers.
Errors in a geography paper and in a computing paper are the latest to come to light.
Both of the AS-level papers were set by the AQA exam board, one of England's biggest awarding bodies.
Exams regulator Ofqual has issued a warning to the UK's exam boards to implement urgent extra checks following a string of blunders.
In total, Ofqual says it is now investigating six mistakes in this year's exam, the majority of which were in AS-level papers.
Ofqual chief executive Glenys Stacey has condemned the errors as "disappointing and unacceptable".
Students sitting the AQA geography exam on May 24 were given the wrong information in a question worth four marks which asked them to label the fastest part of the river.
All candidates will be awarded full marks for the question, AQA said.
Sixth-formers taking the computing paper on Tuesday were faced with an arrow in a diagram that was shorter than it should have been.
AQA said markers would take into account the effect this may have had on candidates' answers. A spokeswoman for the exam board said: "We are very sorry for these mistakes and will ensure that no students will be disadvantaged as a result."