The central dog is an old 1950s concept that is obsolete and should be removed from the text box of the 2010s. It states that the flow of information from DNA->RNA->protein is unidirectional
Examples that goes against this idea are
Reverse transcriptase which transcribes RNA -> DNA. Reverse transcriptase was originally found in RNA viruses. But has since been found in transposons which can be though of viruses that permanently resides in the host cell.
Telomerase... uses to elongate the ends of chromosomes from becoming shorter (something that occurs on the lagging strand of DNA during DNA synthesis) the shRNA used by this enzyme only encodes a few base pairs (6-8bp depending on kingdom)... but it is an example of RNA->DNA
RNA dependent RNA polymerase RNA-> RNA (No DNA is required to make more RNA). has been found in yeast.. with the role of maintaining the centromere... and likely will be found in humans too, since centromeric structure is believed to be conserved in the broad sense.
Prions. Where a prion serves as the template to cause a normal protein prion protein (PrPc) to undergo a change in folding and become the infectious prion (PrPsc). An example information in propagating between protein molecules. Protein-> protein
Then there is epigenetics... where proteins can leave methylation marks on genes (DNA)... changing the expression of the gene in an inheritable way. So information from proteins can flow upwards. While not DNA bases are changed, the DNA is modified. Protein -> DNA
There is also histone modification.. which can be inheritable depending on gene. But it is regulation of DNA by controlling how available that DNA is to being read by transcription machinery.
Then there is siRNA... which can and does modify gene activity. A weaker example of how information can flow from RNA -> DNA.
Next are proteins called cytidine deaminases. These proteins naturally convert cytidine to uracil. APOBEC modifies RNA.. creating a premature stop and thus a shorter APO-B protein with lower activity.. regulating lipid metabolism. So mRNA editing by APOBEC proteins changing the information in RNA aka Protein -> RNA. Next is AID, another cytidine deaminase but one that targets DNA. It used by the immune system to cause hypermutation and thus variation in the antibodies. A poor example of protein inducing genetic changes. Not controlled unlike the DNA methylation example.
Lastly there are ribozymes. RNA that have catalytic activity. So no need for the protein to catalyses a reaction.. RNA can do it on its own.