There are many lines tendered by HSL and run with HSL-coloured blue buses that leave the HSL area. These are not U lines; those are discussed separately. Perhaps the most well-known example is Järvenpää, which lies between Jokela and the rest of Tuusula and Kerava. This anomaly allows you to travel with an HSL ticket on trains and certain buses entirely within Järvenpää.
987A, 989A, V: These services combine to form one return service in the morning and one in the afternoon extended out to Monninkylä in Askola, to provide school tranport. Only seven stops are located in Askola, all of which are outside HSL zones.
969X: Replacement bus 969X stops at platform seven in Hyvinkää, which has been given the HSL stop code Hy6199.
Z: Just like with the D, R and T trains at Riihimäki, the platforms at Lahti (1 and 2-4) have HSL stop codes, despite only VR tickets being valid.
U193: The last northbound stop on this roundabout route (Uusikylä) is in Lohja, however its stop code is prefixed with So, which (incorrectly) implies it is in Siuntio, though it is in zone D.
916: Between Immulantie and Väinöläntie, line 916 spends just a few minutes (and one stop, Herrdahlintie) in Lohja. Herrdahlintie's stop code is prefixed with So, which (incorrectly) implies it is located in Siuntio. This routing anomaly is because it is the most direct route, which means the whole route is in zone D.
665(A, K, N), 967(K): The last (except on line 665A) four stops (Ohkolan sairaala, Poutalantie, Nummelantie and Hyökännummi) are located within Mäntsälä, but zone D has been extended around them. Line 665A extends further (see below)
665A: The last 31 stops (25 minutes of route) are located within Mäntsälä. After Hyökännummi (see above), stops are no longer located in zone D and HSL card readers on buses stop working. However, if you have a mobile ticket valid in zone D, you can travel anywhere along the route, including entirely in Mäntsälä. The first morning departure from Hyrylä extends an additonal 10 minutes after Mäntsälä to serve nearby schools.
989(A): The westbound Linjatie bus stop is in Mäntsälä only because of border anomalies, so it is still in zone D.
Z: Just like the D, R and T trains, the platforms at Mäntsälä have HSL stop codes, despite only VR tickets being valid.
U455(A), U456(A, N), U457(A), U459: These U lines' first/last stop in the HSL area, Metsäkyläntie, is barely in Numrijärvi, and the border of zone C is extended around it.
961: This line runs right into the centre of Nurmijärvi, in the same way as line 665A (see Mäntsälä). 13 Nu-prefixed stops give around 10 minutes of travel time outside HSL zones
964(K): After Palojoki, the last stop in Tuusula, line 964 runs for six minutes outside the HSL area without stopping, before terminating at Lepomäentie, again barely in Nurmijärvi but still in zone D, before becoming a 964(K) completing the long loop back towards Hyrylä.
965(K): In the middle of its route, this line serves six stops in Nurmijärvi, because it is more efficient to run through Nurmijärvi than to double back through Tuusula. HSL tickets including zone D are valid at these six stops as if they were in zone D.
966: While it doesn't technically leave the HSL area in service, its last stop (Terrisuon kuntaraja) is literally on the border of Tuusula and Nurmijärvi and the bus has to turn around on the border.
Z: Just like the D, R and T trains, the platforms at Henna have HSL stop codes, despite only VR tickets being valid. However, the stop codes are prefixed with La, which (incorrectly) implies that they are located in Lahti.
787(B, K): This long line terminates at Pornainen, with the last 15 stops also being in the municipality. HSL tickets are not accepted in Pornainen.
787A: The last 25 minutes (20 stops) of this 90-minute long route are in Pornainen. Unlike the base route (787, see above), it diverts via Laukkoski and extends past Pornainen to Halkia. HSL tickets are not accepted in Pornainen.
987(T): This hour-long route diverts for 20 minutes and 20 stops through Pornainen on its way between Järvenpää and Nikkilä. Because it is the most direct line for many areas along the route, HSL tickets are valid in Pornainen only if your journey starts and ends within the HSL area; you cannot leave or join the service in Pornainen with an HSL ticket. Additionally, the Maisala and Brusas th. stops are in zone D, despite being in Pornainen.
987A: This route has 15 stops on its journey between Järvenpää and Askola (see above). Combined, line 987A spends almost half of its time outside the HSL area. Additionally, the Maisala and Brusas th. stops are in zone D despite being in Pornainen.
987B: This short route has 20 stops (exactly half of its route) in Pornainen, again with no HSL ticket acceptance.
989: This 40-minute route goes through four municipalities: 16 stops in Järvenpää, 1 in Mäntsälä (see above), 7 in Tuusula (though not in zone D) and 26 in Pornainen (also not in zone D).
989A: This line travels through five municipalities: 16 stops in Järvenpää, 1 in Mäntsälä (see above), 7 in Tuusula (though not in zone D), 26 in Pornainen and 7 in Askola (see above). Only about a quarter of its route is within HSL zones.
989B: This short 20-minute route is entirely in Pornainen, making it one of two routes operated for HSL with HSL blue buses where HSL tickets are not accepted anywhere along the route.
989V: This 20-minute route is mostly in Pornainen, save for seven stops in Askola (see above), making it one of two routes operated for HSL with HSL blue buses where HSL tickets are not accepted anywhere along the route.
788(B, K): The easternmost 28 stops are located outside of HSL's zones, in the municipality of Porvoo. The terminus is platform eight at Porvoo's bus station, also the terminus of line U848. HSL tickets are not accepted anywhere in Porvoo.
U848: This U line share its last few stops in Porvoo with line 788(B, K) (see above) and these are acknowleged by HSL, making it the only U line (with U999) that has stops with HSL codes outside the HSL area. Like all other U lines, tickets are only accepted within the HSL area.
969X: Replacement bus 969X terminates at platform six in Riihimäki, which has been given the HSL stop code Ri6198.
.245A: Line 245A's last stop, Kattila (E6935) is technically in Vihti, but zone C is bent around it. However, this line only runs May-October.